Add check for internal connection

[kirtangajjar]

Description of the Change

Adds a check to see if a connection is internal and if it's not, exits early.

Closes #1157

How to test the Change

1. Open a URL with invalid connection id like: admin.php?page=pull&connection_type=external&connection_id=1.
2. Check debug log and ensure that the no warning is shown.
3. Open a URL with external connection and open it's screen as in step 1.
4. Check debug log and ensure that the no warning is shown.
5. Open a URL with network connection and open it's screen as in step 1
6. Check debug log and ensure that the no warning is shown.

Changelog Entry

Fixed - Warning on invalid connection id

Credits

Props @kirtangajjar

Checklist:

• I agree to follow this project's Code of Conduct.
• All new and existing tests pass.

[github-actions]

@kirtangajjar thanks for the PR! Could you please fill out the PR template with description, changelog, and credits information so that we can properly review and merge this?

[peterwilsoncc]

This change looks good and tests well. Thanks Kirtan.

The failing E2E tests look to be due to markup changes in the editor rather than related to this pull request.