CI: Only carry forward full-suite test coverage

[frenck]

Proposed change

It seems like we are now using the "carry forward" feature of Codecov backwards.

In order to carry forward coverage, flags must be used and the carryforward setting must be set for that flag. If that matches, the test coverage can be carried forward to the next coverage result.

Right now, we only set flags on a partial build, thus only partial coverage is carried forward, causing coverage to be incomplete in sequential coverage calculation.

This PR flips this around, we still set flags for each integration (as they are nicely identified in the Codecov UI), but we also now set a full-suite flag for the full CI run. Adding to that a change to the codecov settings: full-suite is carried forward, while all other flags are not.

This should allow us to carry forward the full suite result to partial builds; hopefully solving the low coverage problems we see on some PRs.

codecode.yaml validated using:

cat codecov.yml | curl --data-binary @- https://codecov.io/validate

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

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• This PR fixes or closes issue: fixes #
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