Remove access_level index from runner. Add protected on ci_pipelines. Add protected index on ci_builds.

Solution 1. Persists protected(ref) flag on ci_pipelines table. builds_for_shared_runner and builds_for_specific_runner read the flag instead of executing protected_for? one by one.

An upcoming update to rubocop-gitlab-security added additional
violations.

As its hard right now to determine what is a good metric and whats not,
these two are not listed in the docs, nor will they get a CHANGELOG
entry.

This reverts commit 5ec3b63bfc6f341df040ae08be4858c7181bcacf.

* Use `_total` naming convention.
* Add to metrics documentation.

Also make sure pipeline would also check against tag as well