Revert "[gsutil] Update gsutil error message on outdated boto"

This reverts commit dfafd0a3c7.

Reason for revert: gsutil.py was changed to be non-executable, this is breaking all of our builds which rely on gsutil.py. Example: https://ci.chromium.org/ui/p/flutter/builders/prod/Mac_arm64%20flutter_packaging_test

If making it non-executable was intended, feel free to close this.

Original change's description:
> [gsutil] Update gsutil error message on outdated boto
>
> Add information where .boto file is located
>
> Change-Id: Id8605196ab0906a594bbb0c87a016986415eedac
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4787527
> Reviewed-by: Aravind Vasudevan <aravindvasudev@google.com>
> Commit-Queue: Josip Sokcevic <sokcevic@chromium.org>

Change-Id: I88e0a993a67a85e3c81799f6f3f128c4f9276ff7
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4791811
Commit-Queue: Josip Sokcevic <sokcevic@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Reviewed-by: Josip Sokcevic <sokcevic@chromium.org>

gsutil.py

@@ -266,7 +266,7 @@ def run_gsutil(target, args, clean=False):
           '\n' + separator + '\n' +
           'Warning: You might have an outdated .boto file. If this issue '
           'persists after running `gsutil.py config`, try removing your '
-          '.boto, usually located in your home directory.\n' + separator + '\n',
+          '.boto file.\n' + separator + '\n',
           file=sys.stderr)
 
     _print_subprocess_result(p)