Fix broken codecov reports

[t92549]

The codecov bot has been commenting very strange results for a while now and we were not sure why, example: https://github.com/gchq/Gaffer/pull/2709#issuecomment-1184543574. In this linked PR, one line has changed in a test but the reports shows completely different files changed.

The strange results often ends up in the bot being ignored, so it should be fixed.

I have discovered that the root of the issue is that the ci workflow (which tests the code and uploads coverage) is not run on develop, therefore, there is not an up to date report to compare against.

I think we should update the ci action to:

• run on develop and v2-alpha
• use codecov/codecov-action@v3

As well as deleting the bugged historical reports.

[t92549]

Alternatively we could look into codacy

[t92549]

As an additional explanation to the above: I think the pattern of effectively having 2 develop branches (develop and v2-alpha) also can break codecov.

For a proper fix, we need to:

• merge v2-alpha into develop (release 2.0.0)
• make the coverage upload run on develop
• delete the bugged historical reports

[GCHQDeveloper314]

As we are not using the GitHub App Integration it seems that codecov will no longer work after May 2023. Unless the Github App Integration is installed (more info here).

Another option would be to use a GitHub Action for coverage - this wouldn't be as full featured.

[t92549]

Since the CI now does run on develop, I think this issue should just track the move to the GitHub App as suggested by @GCHQDeveloper314

[t92549]

Fixed by https://github.com/gchq/Gaffer/pull/2953