tooling: test-js-with-puppeteer: Accept full relative file path.

Changes in a529dc8 to raise exception for invalid file name
has removed support for passing full file paths.
This commit fixes it.

Thanks to Steve Howell (showell) for reporting this.

tools/lib/test_script.py

@@ -106,19 +106,19 @@ def add_provision_check_override_param(parser: ArgumentParser) -> None:
 def find_js_test_files(test_dir: str, files: Iterable[str]) -> List[str]:
     test_files = []
     for file in files:
-        relative_file_path = min(
+        file = min(
             (
                 os.path.join(test_dir, file_name)
                 for file_name in os.listdir(test_dir)
                 if file_name.startswith(file)
             ),
-            default=None,
+            default=file,
         )
 
-        if relative_file_path is None:
+        if not os.path.isfile(file):
             raise Exception(f"Cannot find a matching file for '{file}' in '{test_dir}'")
 
-        test_files.append(os.path.abspath(relative_file_path))
+        test_files.append(os.path.abspath(file))
 
     if not test_files:
         test_files = sorted(