Always set CodeCov notifications to green/passing

[wilzbach]

As the dlang-bot now won't merge a PR when there's one failure [1], it makes sense
to force CodeCov to be informational. The interesting bit - coverage of the diff -
is still displayed in the CI tab and more importantly the browser extension still
works too and will continue to highlight the uncovered parts in red.

See also: https://github.com/dlang/dmd/blob/master/.codecov.yml

[1] dlang/dlang-bot#69

[dlang-bot]

Thanks for your pull request, @wilzbach!

[MartinNowak]

Didn't we figure that only patch coverage is relevant?
Can we just use status: { patch: { default: { threshold: 5 } } } instead? That should allow patch coverage to be a bit (5 per-cent points) lower than project coverage, but fails (and requires manual review) if it's even lower.
All the other coverage statuses seem superfluous.

[wilzbach]

Yes, but there seems to be a bug at CodeCov which leads to it not showing up at all. I haven't had time to report this to the CodeCov team, but that's what's happening at dmd atm.

[MartinNowak]

Crazy amount of configuration.

[wilzbach]

Didn't we figure that only patch coverage is relevant?

I re-thought this and the error we experience at DMD is actually related to us using multiple builds, so we can safely use only CodeCov patch here.

[wilzbach]

The Jenkins failure is unrelated - see dlang/ci#135