Enable Lint/RedundantWithIndex cop for HAML

What does this MR do?

Enables Lint/RedundantWithIndex cop for HAML, which follows the fix a lint introduced in gitlab-foss!4424 (merged) in %8.10 (5 years ago).

Part of #23855

Screenshots (strongly suggested)

n/a

Does this MR meet the acceptance criteria?

Conformity

• 📋 Does this MR need a changelog?
  • I have not included a changelog entry because frontend ~"technical debt" around static code analysis.
• Code review guidelines
• Style guides
• Separation of EE specific content