Fix skip-issue-check to support short issue references (#123) (#25260)

Updates the PR issue check to recognize both full GitHub issue URLs and
short issue references in the format `#123`.

## Problem
Currently, the `skip-issue-check` workflow only accepts full GitHub
issue URLs like `https://github.com/microsoft/vscode-python/issues/123`
in PR descriptions. Contributors using the more common short format like
`#123` would need to add the `skip-issue-check` label to bypass the
check.

## Solution
Modified the GitHub Actions script in
`.github/workflows/pr-file-check.yml` to check for both formats:
- Full URLs: `https://github.com/microsoft/vscode-python/issues/123`
(existing behavior)
- Short references: `#123` (new behavior)

The check now passes if either format is found in the PR description.

## Changes
- Added regex pattern `/#\d+/` to match short issue references
- Updated condition to pass if either format is detected: `if
(!issueLink && !issueReference)`
- Maintains backward compatibility and existing `skip-issue-check` label
behavior

## Testing
Verified the updated logic handles all scenarios correctly:
- ✅ Full GitHub URLs (existing)
- ✅ Short format like `#123` (new)
- ✅ Both formats in same PR description
- ✅ Multiple short references
- ✅ Skip label behavior unchanged
- ❌ No issue references (correctly fails)
- ❌ Invalid formats like `#` without numbers (correctly fails)

Fixes #25259.

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Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: eleanorjboyd <[email protected]>

Author: Copilot

.github/workflows/pr-file-check.yml

@@ -51,7 +51,8 @@ jobs:
             if (!labels.includes('skip-issue-check')) {
               const prBody = context.payload.pull_request.body || '';
               const issueLink = prBody.match(/https:\/\/github\.com\/\S+\/issues\/\d+/);
-              if (!issueLink) {
+              const issueReference = prBody.match(/#\d+/);
+              if (!issueLink && !issueReference) {
                 core.setFailed('No associated issue found in the PR description.');
               }
             }