[New Feature]: Wingetbot should not retry the validation completed label when a check is pending

Nobody has claimed this yet.

### Description of the new feature/enhancement

When the CLA check is pending and a PR has completed validation and is ready for merge, wingetbot will repeatedly remove and re-add https://github.com/microsoft/winget-pkgs/labels/Validation-Completed in an attempt to trigger the merge. However, this merge will never happen because of the pending check.

e.g. https://github.com/microsoft/winget-pkgs/pull/373873

### Proposed technical implementation details (optional)

When the checks status of any check on a PR is `Pending` - wingetbot should skip removing and re-adding the Validation-Completed Label https://github.com/microsoft/winget-pkgs/labels/Validation-Completed

Locate wingetbot's pull-request check-status handling and the logic that removes and re-adds the Validation-Completed label. Start by tracing the pending-check path, then run the relevant wingetbot tests or checks. Done means a PR with any pending check does not trigger those label operations, while existing behavior remains unchanged otherwise.

Written by the indexing model from the issue text.