fix: issue counts incorrect when HIDE_TIME_TO_CLOSE is True

[zkoppert]

Pull Request

Fixes #310

Proposed Changes

This pull request improves the get_per_issue_metrics function in issue_metrics.py by ...

• Expanding the test coverage in test_issue_metrics.py to cover counting logic when env vars are set
• Changing the issue counting logic so it is not gated by the HIDE_TIME_TO_CLOSE env var

Readiness Checklist

Author/Contributor

• If documentation is needed for this change, has that been included in this pull request
• run make lint and fix any issues that you have introduced
• run make test and ensure you have test coverage for the lines you are introducing
• If publishing new data to the public (scorecards, security scan results, code quality results, live dashboards, etc.), please request review from @jeffrey-luszcz

Reviewer

• Label as either fix, documentation, enhancement, infrastructure, maintenance, or breaking