Add tools/internal_ci/ to test filter

tools/run_tests/python_utils/filter_pull_request_tests.py

@@ -98,6 +98,7 @@ _WHITELIST_DICT = {
   '^test/distrib/php/': [_PHP_TEST_SUITE],
   '^test/distrib/python/': [_PYTHON_TEST_SUITE],
   '^test/distrib/ruby/': [_RUBY_TEST_SUITE],
+  '^tools/internal_ci/': [],
   '^vsprojects/': [_WINDOWS_TEST_SUITE],
   'binding\.gyp$': [_NODE_TEST_SUITE],
   'composer\.json$': [_PHP_TEST_SUITE],