CI: Tweak our code coverage profile behavior

[mattlord]

Description

This PR makes the following changes:

1. Adds a repo/project level codecov configuration file (./codecov.yml) to tweak the settings based on our early experiences
2. Adds the -coverpkg=vitess.io/vitess/go/... flag to our go test invocation to better calculate package level coverage when testing is done across packages
3. Adds the -covermode=atomic flag to our go test invocation to support parallel work
4. Increases the GitHub Actions runner size for the code coverage workflow to match what we use for the unit race workflows as the the code coverage workflow — which has, now cross package, coverage profiling enabled — is also heavier than the basic unit test workflows and processes were often getting killed
5. Modifies the codecov GitHub Actions workflow params so that the output is verbose and if we fail to upload the report it causes the workflow to fail
6. Moves the codecov GitHub Actions workflow from using v3 of the action to v4. This replaces the previous universal-uploader with usage of the codecov CLI. The issue we had seen was that once we enabled the cross package coverage, we saw this error when uploading the report:
   Could not read coverage file (coverage.out): Error: There was an error reading the coverage file: Error: Cannot create a string longer than 0x1fffffe8 characters

Related Issue(s)

• Follow-up to: CI: Re-enable FOSSA scan and add Codecov #14333

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

[vitess-bot]

Review Checklist

Hello reviewers! 👋 Please follow this checklist when reviewing this Pull Request.

General

• Ensure that the Pull Request has a descriptive title.
• Ensure there is a link to an issue (except for internal cleanup and flaky test fixes), new features should have an RFC that documents use cases and test cases.

Tests

• Bug fixes should have at least one unit or end-to-end test, enhancement and new features should have a sufficient number of tests.

Documentation

• Apply the release notes (needs details) label if users need to know about this change.
• New features should be documented.
• There should be some code comments as to why things are implemented the way they are.
• There should be a comment at the top of each new or modified test to explain what the test does.

New flags

• Is this flag really necessary?
• Flag names must be clear and intuitive, use dashes (-), and have a clear help text.

If a workflow is added or modified:

• Each item in Jobs should be named in order to mark it as required.
• If the workflow needs to be marked as required, the maintainer team must be notified.

Backward compatibility

• Protobuf changes should be wire-compatible.
• Changes to _vt tables and RPCs need to be backward compatible.
• RPC changes should be compatible with vitess-operator
• If a flag is removed, then it should also be removed from vitess-operator and arewefastyet, if used there.
• vtctl command output order should be stable and awk-able.

[dbussink]

Should we exclude all cached_size.go files as well as generated code?

[mattlord]

Added here: 56f139f

Please let me know if you think we should remove any of the added ignore lines. Thanks!

[harshit-gangal]

As discussed earlier, can we disable codecov comments on the file changes.

[mattlord]

As discussed earlier, can we disable codecov comments on the file changes.

This page notes how we can toggle them on and off in the PR's Changed Files view, as well as how we can disable them entirely: https://docs.codecov.com/docs/github-checks#hiding-annotations-in-the-files-view

Do you think that we should disable them globally or make it more well known how to toggle them on and off during PR review? I'm OK either way. You can also see the untested lines in a better UI when you view the commit in codecov using the link added to main codecov PR comment. For example (click on a file): https://app.codecov.io/gh/vitessio/vitess/pull/15096

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (aecf793) 47.80% compared to head (c2fe9d2) 70.63%.
Report is 4 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main   #14967       +/-   ##
===========================================
+ Coverage   47.80%   70.63%   +22.82%     
===========================================
  Files        1155     1375      +220     
  Lines      240308   182222    -58086     
===========================================
+ Hits       114890   128715    +13825     
+ Misses     116846    53507    -63339     
+ Partials     8572        0     -8572     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[ajm188]

i think we should ignore generated protobuf stuff, too; otherwise lgtm!

[ajm188]

just stating for posterity that i'm good with this given that https://docs.codecov.com/docs/github-checks#hiding-annotations-in-the-files-view exists

[frouioui]

Had no idea this existed, but tested and approved

[frouioui]

LGTM, thanks a bunch @mattlord