[sw/testing] move smoke tests and condense their names

This partially addresses #7976, specifically the tasks that states:
  1. "The smoke tests subfolder will be deprecated, and all smoke tests
       will move to sw/device/tests."
  2. "The prefix "dif_", will be removed from smoke test file names."

Additionally, all build and test configuration files were updated to
match the above the changes.

Signed-off-by: Timothy Trippel <ttrippel@google.com>
diff --git a/test/systemtest/earlgrey/silicon_creator_config.py b/test/systemtest/earlgrey/silicon_creator_config.py
index 92da071..3b09b2c 100644
--- a/test/systemtest/earlgrey/silicon_creator_config.py
+++ b/test/systemtest/earlgrey/silicon_creator_config.py
@@ -19,7 +19,7 @@
 #   on all targets if not given (optional).
 TEST_SILICON_CREATOR_APPS_SELFCHECKING = [
     {
-        "name": "dif_uart_smoketest",
+        "name": "uart_smoketest",
         "signing_key": "fpga_key_1",
     },
 ]