Remove in_app_hand_raise_pql PQL feature flags

What does this MR do and why?

Cleanup PQL feature flags in_app_hand_raise_pql

We have replaced the contact sales link with an in App modal in 14.3. Now we can remove the flag we added for stability.

• Rollout #343311 (closed)
• Issue #344522 (closed)

Related customersdot MR https://gitlab.com/gitlab-org/customers-gitlab-com/-/merge_requests/4141

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