Enable new Performance/* cops

What does this MR do and why?

This MR enables all pending Performance/* cops:

• Performance/ConcurrentMonotonicTime
• Performance/MapCompact
• Performance/RedundantEqualityComparisonBlock
• Performance/RedundantSplitRegexpArgument
• Performance/StringIdentifierArgument

See gitlab-org/gitlab!105850 (merged) to test these cops on gitlab-org/gitlab.

Contributes to #40.