Prune unused code from bazel_to_cmake. (#9188)

History, thanks to `git log -S [search_string]`:

* `iree_e2e_cartesian_product_test_suite` was replaced with other test suites in https://github.com/google/iree/pull/8078
* `spirv_kernel_cc_library` is unused since https://github.com/google/iree/pull/1533
* `MLIRExecutionEngine` is unused since https://github.com/google/iree/commit/49dc151dd5539197f4a8174992c508cbb3a78af6
diff --git a/build_tools/bazel_to_cmake/bazel_to_cmake_converter.py b/build_tools/bazel_to_cmake/bazel_to_cmake_converter.py
index d988040..3ee6f8a 100644
--- a/build_tools/bazel_to_cmake/bazel_to_cmake_converter.py
+++ b/build_tools/bazel_to_cmake/bazel_to_cmake_converter.py
@@ -162,28 +162,6 @@
   return _convert_string_list_block(list_name, targets, sort=True, quote=False)
 
 
-# Copied from integrations/tensorflow/e2e/iree_e2e_cartesian_product_test_suite.bzl
-def _normalize_dictionary(dictionary):
-  """Wraps every value of dictionary in a list if it isn't one already."""
-  for key, value in dictionary.items():
-    if type(value) != type([]):
-      dictionary[key] = [value]
-  return dictionary
-
-
-def _dictionary_product(dictionary):
-  """Returns a named cartesian product of dictionary's values."""
-
-  # Converts {'a': [1, 2], 'b': [3, 4]} into
-  # [{'a': 1, 'b': 3}, {'a': 1, 'b': 4}, {'a': 2, 'b': 3}, {'a': 2, 'b': 4}]
-  product = [[]]
-  for values in dictionary.values():
-    # Iteratively grow the elements of the product.
-    product = [element + [value] for element in product for value in values]
-  dicts = [{k: v for k, v in zip(dictionary, element)} for element in product]
-  return dicts
-
-
 class BuildFileFunctions(object):
   """Object passed to `exec` that has handlers for BUILD file functions."""
 
@@ -439,15 +417,6 @@
                             f"{flatten_block}"
                             f"  PUBLIC\n)\n\n")
 
-  def spirv_kernel_cc_library(self, name, srcs):
-    name_block = _convert_string_arg_block("NAME", name, quote=False)
-    srcs_block = _convert_srcs_block(srcs)
-
-    self.converter.body += (f"iree_spirv_kernel_cc_library(\n"
-                            f"{name_block}"
-                            f"{srcs_block}"
-                            f")\n\n")
-
   def iree_bytecode_module(self,
                            name,
                            src,
@@ -677,64 +646,6 @@
                             f"{target_cpu_features_variants_block}"
                             f")\n\n")
 
-  def iree_e2e_cartesian_product_test_suite(self,
-                                            name,
-                                            matrix,
-                                            failing_configurations=None,
-                                            tags=None,
-                                            data=None,
-                                            **kwargs):
-    # Note kwargs deps, size, python_version are unused
-    if data is not None:
-      self._convert_unimplemented_function(
-          "iree_e2e_cartesian_product_test_suite", name + " has data")
-
-    matrix_keys = matrix.keys()
-
-    name_block = _convert_string_arg_block("NAME", name, quote=False)
-    matrix_keys_block = _convert_string_list_block("MATRIX_KEYS", matrix_keys)
-    labels_block = _convert_string_list_block("LABELS", tags)
-
-    value_strings = []
-    for key in matrix_keys:
-      # ensure matching order
-      values = matrix[key]
-      if not isinstance(values, list):
-        values = [values]
-      if not values:
-        self._convert_unimplemented_function(
-            "iree_e2e_cartesian_product_test_suite",
-            name + f" has empty list for matrix key {key}")
-      value_strings.append(";".join(str(value) for value in values))
-    matrix_values_block = _convert_string_list_block("MATRIX_VALUES",
-                                                     value_strings)
-
-    # Copied from integrations/tensorflow/e2e/iree_e2e_cartesian_product_test_suite.bzl
-    failing_configurations_block = ""
-    if failing_configurations is not None:
-      failing_matrix_configurations = []
-      for failing_configuration in failing_configurations:
-        failing_configuration = _normalize_dictionary(failing_configuration)
-
-        failing_matrix_configurations.extend(
-            _dictionary_product(failing_configuration))
-
-      failing_configuration_strings = []
-      for failing_configuration in failing_matrix_configurations:
-        failing_config_string = ",".join(
-            str(failing_configuration.get(key, "")) for key in matrix_keys)
-        failing_configuration_strings.append(failing_config_string)
-        failing_configurations_block = _convert_string_list_block(
-            "FAILING_CONFIGURATIONS", failing_configuration_strings)
-
-    self.converter.body += (f"iree_e2e_cartesian_product_test_suite(\n"
-                            f"{name_block}"
-                            f"{matrix_keys_block}"
-                            f"{matrix_values_block}"
-                            f"{failing_configurations_block}"
-                            f"{labels_block}"
-                            f")\n\n")
-
   def native_test(self, name, src, args=None, data=None, tags=None):
     if data is not None:
       self._convert_unimplemented_function("native_test", name + " has data")
diff --git a/build_tools/bazel_to_cmake/bazel_to_cmake_targets.py b/build_tools/bazel_to_cmake/bazel_to_cmake_targets.py
index 8554c89..df73456 100644
--- a/build_tools/bazel_to_cmake/bazel_to_cmake_targets.py
+++ b/build_tools/bazel_to_cmake/bazel_to_cmake_targets.py
@@ -45,7 +45,6 @@
     "@llvm-project//mlir:CFGTransforms": ["MLIRSCFToControlFlow"],
     "@llvm-project//mlir:ComplexDialect": ["MLIRComplex"],
     "@llvm-project//mlir:DialectUtils": [""],
-    "@llvm-project//mlir:ExecutionEngineUtils": ["MLIRExecutionEngine"],
     "@llvm-project//mlir:GPUDialect": ["MLIRGPUOps"],
     "@llvm-project//mlir:GPUTransforms": ["MLIRGPUTransforms"],
     "@llvm-project//mlir:LinalgInterfaces": ["MLIRLinalg"],
@@ -67,7 +66,6 @@
     "@llvm-project//mlir:SPIRVDialect": ["MLIRSPIRV"],
     "@llvm-project//mlir:TosaDialect": ["MLIRTosa"],
     "@llvm-project//mlir:ToLLVMIRTranslation": ["MLIRTargetLLVMIRExport"],
-    "@llvm-project//mlir:mlir_c_runner_utils": ["MLIRExecutionEngine"],
     "@llvm-project//mlir:mlir-translate": ["mlir-translate"],
     "@llvm-project//mlir:MlirTableGenMain": ["MLIRTableGen"],
     "@llvm-project//mlir:MlirOptLib": ["MLIROptLib"],