Disable joins for approval rules group users

Summary

Disable joins for approval rules group users.

• MR: Disable joins for ApprovalRuleLike.group_users (!136588 - merged)
• Issue: [Feature flag] Rollout of `approval_rules_disab... (#431564 - closed)

Metrics

We can use the approvalRules GraphQL request to track the performance implication: https://log.gprd.gitlab.net/app/r/s/iJMwZ.

Before

• Average json.duration_s: 0.36s
• Median json.duration_s: 0.27s
• Average json.db_count: 65.75
• Median json.db_count: 56.2

After

• Average json.duration_s: 0.34s
• Median json.duration_s: 0.25s
• Average json.db_count: 69.35
• Median json.db_count: 60

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json.db_count slightly increased while json.duration_s slightly decreased