Pythonify extract_metadata_from_bazel_xml.py (#30796)

Autodetected improvements.

tools/buildgen/extract_metadata_from_bazel_xml.py

@@ -759,9 +759,9 @@ def _generate_build_extra_metadata_for_tests(
             platforms.append('linux')
             platforms.append(
                 'posix')  # there is no posix-specific tag in bazel BUILD
-            if not 'no_mac' in bazel_tags:
+            if 'no_mac' not in bazel_tags:
                 platforms.append('mac')
-            if not 'no_windows' in bazel_tags:
+            if 'no_windows' not in bazel_tags:
                 platforms.append('windows')
             test_dict['platforms'] = platforms
 
@@ -788,7 +788,7 @@ def _generate_build_extra_metadata_for_tests(
     tests_by_simple_name = {}
     for test_name, test_dict in list(test_metadata.items()):
         simple_test_name = test_dict['_RENAME']
-        if not simple_test_name in tests_by_simple_name:
+        if simple_test_name not in tests_by_simple_name:
             tests_by_simple_name[simple_test_name] = []
         tests_by_simple_name[simple_test_name].append(test_name)