CMake: Fix test labels

Prior to the changes all `_` in the path got replaced with `/`:

Before:
```
  Test  #30: iree/test/e2e/linalg/path:pw_add.mlir.test
  Test  #31: iree/test/e2e/linalg/path:pw_add_mul.mlir.test
  Test  #32: iree/test/e2e/linalg/path:pw_add_multiwg.mlir.test
  Test  #33: iree/test/e2e/linalg/path:reduce.mlir.test

  Test #268: iree/samples/custom/modules:custom_modules_test
  Test #269: iree/samples/custom/modules/dialect/test:conversion.mlir.test
  Test #270: iree/samples/custom/modules/dialect/test:custom_ops.mlir.test
  Test #271: iree/samples/simple/embedding:simple_embedding_test
```

After:
```
  Test  #30: iree/test/e2e/linalg_path:pw_add.mlir.test
  Test  #31: iree/test/e2e/linalg_path:pw_add_mul.mlir.test
  Test  #32: iree/test/e2e/linalg_path:pw_add_multiwg.mlir.test
  Test  #33: iree/test/e2e/linalg_path:reduce.mlir.test

  Test #268: iree/samples/custom_modules:custom_modules_test
  Test #269: iree/samples/custom_modules/dialect/test:conversion.mlir.test
  Test #270: iree/samples/custom_modules/dialect/test:custom_ops.mlir.test
  Test #271: iree/samples/simple_embedding:simple_embedding_test
```

Closes https://github.com/google/iree/pull/1360

COPYBARA_INTEGRATE_REVIEW=https://github.com/google/iree/pull/1360 from iml130:cmake-test-labels 34dc25d1345980411b2914defb0cd3455613dc91
PiperOrigin-RevId: 304524688
diff --git a/build_tools/cmake/iree_lit_test.cmake b/build_tools/cmake/iree_lit_test.cmake
index bdcde49..430dc7f 100644
--- a/build_tools/cmake/iree_lit_test.cmake
+++ b/build_tools/cmake/iree_lit_test.cmake
@@ -58,13 +58,15 @@
     endif()
   endforeach(_DATA_DEP)
 
-  # We run all our tests through a custom test runner to allow setup and teardown.
-  string(REPLACE "_" "/" _PACKAGE_PATH ${_PACKAGE_NAME})
+  iree_package_ns(_PACKAGE_NS)
+  string(REPLACE "::" "/" _PACKAGE_PATH ${_PACKAGE_NS})
   set(_NAME_PATH "${_PACKAGE_PATH}:${_RULE_NAME}")
   add_test(
     NAME
       ${_NAME_PATH}
     COMMAND
+      # We run all our tests through a custom test runner to allow setup
+      # and teardown.
       "${CMAKE_SOURCE_DIR}/build_tools/cmake/run_test.${IREE_HOST_SCRIPT_EXT}"
       "${CMAKE_SOURCE_DIR}/iree/tools/run_lit.${IREE_HOST_SCRIPT_EXT}"
       ${_TEST_FILE_PATH}