Handle `GitlabSecurity/PublicSend` offenses in spec code
Problem
As per !303 (diffs, comment 1591912369) the GitlabSecurity/PublicSend
is disabled for spec/**/*.rb
because it's too noisy.
Proposed solution
- Enable the rule for specs again and resolve the offenses OR
- Keep rule disabled permanently and add a code comment to
.rubocop.yml
why it's disabled.