Improve coverage tracking

[Bo98]

• Fix integration test coverage tracking not working properly (would overwrite each other as the unique ID was generated but not read) - this regressed as the fix for Cleanup CodeCov tests output spam #14662 overcombined command names
• Fix brew.rb not being tracked
• Simplify integration test unique ID generation (to avoid regressing back to the state prior to Cleanup CodeCov tests output spam #14662 too much - it will unavoidably have a little but still should be significantly shorter than before)
• Exclude sorbet and yard directories from coverage tracking - these are used in non-brew tools and are out of scope for rspec testing.
• Fix up some regexes and add some groups for livecheck etc.
• Remove RubyGems < 2.2 compatibility code. We already no longer support it:

  brew/Library/Homebrew/utils/gems.rb

  Line 89 in 39c2296

  raise "RubyGems too old!" if Gem::Version.new(Gem::VERSION) < Gem::Version.new("2.2.0")

[Bo98]

72.40% (+5.46%)

[MikeMcQuaid]

Looks great: more coverage less code. Nice work as usual @Bo98!