Migrate code coverage to Harbormaster coverage build plan and off of autoplan

[La0]

As discussed with @marco-c on #1977, we can now migrate the code coverage function use Harbormaster:

• upload_coverage_results
• upload_lint_results

[marco-c]

upload_lint_results could probably be removed altogether now

[marco-c]

(well, after we have the coverage build plan)

[La0]

Bugzilla bug to request a build plan for code review bot

[marco-c]

Bugzilla bug to request a build plan for code review bot

We'll need one for code coverage too to use for fixing this issue