[WIP] Fix integration test teardown / cleanup and missing yarn installation

[raix]

Fix tests and update execa:

• To avoid flakyness due to race conditions: use sync version of remove letting beforeEach and afterAll
• Update execa from v1 to v5 (v6 requires esm so downgraded to v5 for now)
• Added test to make sure yarn is installed (making it easier to debug next time)
• Added npm i -g yarn in github action for integration tests
• Increased the timeout for now in yarn integration test
• Improve run create-react-app output logging output and exit code in github action groups for better insights
• Defer jest test result waiting for stdio to flush

Findings:

• Sometimes yarn connectivity failes after x amount of retries

cc @iansu & @mrmckeb (We should likely squash this one if merging...)