Codecov coverage reporting fixes

[Bronek]

High Level Overview of Change

Make codecov reporting stable by disabling plugins, disabling reporting of src/test and switching partials_as_hits

Context of Change

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactor (non-breaking change that only restructures code)
• Performance (increase or change in throughput and/or latency)
• Tests (you added tests for code that already exists, or your new feature included in this PR)
• Documentation update
• Chore (no impact to binary, e.g. .gitignore, formatting, dropping support for older tooling)
• Release

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70.8%. Comparing base (8b0d049) to head (0a308af).

❗ Current head 0a308af differs from pull request most recent head 69c6917. Consider uploading reports for the commit 69c6917 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           develop   #4977      +/-   ##
==========================================
- Coverage     77.0%   70.8%    -6.2%     
==========================================
  Files         1129     796     -333     
  Lines       132027   66781   -65246     
  Branches     39711   11049   -28662     
==========================================
- Hits        101647   47273   -54374     
+ Misses       24502   19508    -4994     
+ Partials      5878       0    -5878     

see 779 files with indirect coverage changes

[Bronek]

Proposed merge message:

* Amend `.codecov.yml` to disable coverage reporting of tests sources and explicitly set most parameters
* Increase codecov upload retry time to 210s (from 35s)
* Upgrade gcovr adding support for more coverage formats (lcov, clover, jacoco)
* Upgrade github actions in coverage workflow
* Explicitly disable codecov plugins (also removing `gcov` coverage, which is not correctly handled by codecov https://github.com/codecov/feedback/issues/334 )