Replace `INFO` with `FINE` logging in `CoverageOutputGenerator`

[fmeum]

This reduces unconditional log spam for coverage report actions. If needed, users can configure the loglevel by wrapping the CoverageOutputGenerator jar into a java_binary with appropriate jvmopts.

[c-mita]

If needed, users can configure the loglevel by wrapping the CoverageOutputGenerator jar into a java_binary with appropriate jvmopts

I don't think this is a good way to configure logging levels, although I don't see much of an alternative without adding to Bazel's large collection of flags...

[fmeum]

@c-mita Are you going to create a new release after the merge?

[c-mita]

Yes, although I might need to review (or actually formalize) the process first. There's a long standing issue re. provenance (https://github.com/bazelbuild/bazel/issues/15459).

[lalten]

Would it be possible to release a remote_coverage_tools with this fix? The coverage log spam is still making our build logs pretty hard to read.

[fmeum]

@keertk

[keertk]

@c-mita can you take a look?

[lalten]

friendly bump on this