chore(ci): re-enable codecov

[iainsproat]

Description & motivation

CodeCov was broken for a while - it wasn't publishing GitHub checks - and we disabled it.

This PR re-enables CodeCov.

The GitHub checks weren't being published because the default behaviour for CodeCov is to wait until all other CI checks are completed before publishing its own. As we include some optional, manually triggered, jobs in CircleCI there will often be jobs that never complete, which blocks CodeCov from publishing. This PR configures CodeCov not to wait until all CI status are complete before publishing.

Changes:

To-do before merge:

Screenshots:

Validation of changes:

Checklist:

• [ ] My pull request follows the guidelines in the Contributing guide?
• [ ] My pull request does not duplicate any other open Pull Requests for the same update/change?
• [ ] My commits are related to the pull request and do not amend unrelated code or documentation.
• [ ] My code follows a similar style to existing code.
• [ ] I have added appropriate tests.
• [ ] I have updated or added relevant documentation.

References

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 71.05%. Comparing base (8c7ed44) to head (e7144fc). Report is 1378 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #3502 +/- ## ========================================== + Coverage 66.19% 71.05% +4.85% ========================================== Files 273 364 +91 Lines 10724 16117 +5393 Branches 1433 2688 +1255 ========================================== + Hits 7099 11452 +4353 - Misses 3173 3766 +593 - Partials 452 899 +447 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.