Pants ci: Run self-check tests w/ venv generated by pants #5591

Job	Run time
Skip Duplicate Jobs Pre Job	4s
Self-check on Python 3.8 - Python 3.8	6m 51s
Pack Tests - Python 3.8	2m 40s
Lint Checks (black, flake8, etc.) - Python 3.8	3m 13s
Integration Tests (chunk 1) - Python 3.8	4m 34s
Unit Tests (chunk 1) - Python 3.8	5m 7s
Compile (pip deps, pylint, etc.) - Python 3.8	3m 49s
Integration Tests (chunk 2) - Python 3.8	4m 58s
Unit Tests (chunk 2) - Python 3.8	5m 4s
Lint Checks (black, flake8, etc.) - Python 3.9	2m 54s
Unit Tests (chunk 1) - Python 3.9	5m 33s
Pack Tests - Python 3.9	2m 57s
Compile (pip deps, pylint, etc.) - Python 3.9	4m 16s
Integration Tests (chunk 1) - Python 3.9	4m 36s
Unit Tests (chunk 2) - Python 3.9	5m 15s
Integration Tests (chunk 2) - Python 3.9	4m 36s
Slack notification for failed master builds	2s
	1h 6m 29s

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