python: allow using allowed_errors.py (#7719)

See #7718. Fix it by renaming all `types.py` to `common_types.py`.

Additionally, add an advert for using `allowed_errors.py` to test any
added regex.

test_runner/fixtures/pageserver/allowed_errors.py

@@ -131,9 +131,10 @@ if __name__ == "__main__":
         "-i",
         "--input",
         type=argparse.FileType("r"),
-        default=sys.stdin,
-        help="Pageserver logs file. Reads from stdin if no file is provided.",
+        help="Pageserver logs file. Use '-' for stdin.",
+        required=True,
     )
+
     args = parser.parse_args()
     errors = _check_allowed_errors(args.input)