fix(tests): delete flaky test

[punya]

This test is already disabled for current and future versions of NodeJS, and I don't think it's worth putting in the effort to fix flakiness when the whole test will soon be a no-op.

Also fix other issues that were (deterministically) breaking the build:

• Disable codecov: we were running out of API quota, and most other GCP repos had previously disabled it for unrelated reasons
• Migrate eslint ignores from the "node" plugin to the "n" plugin

Fixes #1562, fixes #1525, fixes #1524, fixes #1523, fixes #1522, fixes #1500, fixes #1499, fixes #1498, fixes #1497, fixes #1496

[generated-files-bot[bot]]

Warning: This pull request is touching the following templated files:

• .github/workflows/ci.yaml - .github/workflows/ci.yaml (GitHub Actions) should be updated in synthtool