Fix pipeline template generation from custom git repositories

[kfr2]

Which issue(s) does this change fix?

#4206

Why is this change necessary?

Without this change, custom git repositories cannot be used for pipeline template generation.

How does it address the issue?

This commit restructures the _generate_from_custom_location() function to ensure self._generate_from_pipeline_template() is called within the context manager under which the custom git repository is cloned.

What side effects does this change have?

None.

Mandatory Checklist

PRs will only be reviewed after checklist is complete

• [x] Add input/output type hints to new functions/methods
• [x] Write design document if needed (Do I need to write a design document?)
• [x] Write/update unit tests
• [x] Write/update integration tests
• [x] Write/update functional tests if needed
• [x] make pr passes
• [x] make update-reproducible-reqs if dependencies were changed
• [x] Write documentation

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[mndeveci]

Thanks for raising this PR! Can we add some tests to cover the case which is been fixed by this PR? So that we won't have the same issue by mistake later.

[kfr2]

@mndeveci @aahung Thanks for the feedback! I've added a test case which exercises the interactive workflow operating against a "remote" Git repository.

[kfr2]

@aahung @mndeveci Do y'all need me to do anything else for this pull request? The failing test doesn't seem to be related to anything I've changed.

[lucashuy]

I'll update this branch from develop, that way the tests are restarted 😃