Add tmp index for orphaned approval rules

What does this MR do and why?

This MR adds 2 new indexes needed for Remove orphaned approval rules for imported pro... (!127212 - merged).

Queries

Before adding an index in !127426 (merged):

SELECT "approval_project_rules".* FROM "approval_project_rules" WHERE "approval_project_rules"."report_type" IN (2, 4) AND "approval_project_rules"."security_orchestration_policy_configuration_id" IS NULL

• https://postgres.ai/console/gitlab/gitlab-production-tunnel-pg12/sessions/20623/commands/67668
• https://postgres.ai/console/gitlab/gitlab-production-tunnel-pg12/sessions/20623/commands/67667

After adding an index in !127426 (merged):

SELECT "approval_merge_request_rules".* FROM "approval_merge_request_rules" WHERE "approval_merge_request_rules"."report_type" IN (2, 4) AND "approval_merge_request_rules"."security_orchestration_policy_configuration_id" IS NULL

• https://postgres.ai/console/gitlab/gitlab-production-tunnel-pg12/sessions/20652/commands/67784
• https://postgres.ai/console/gitlab/gitlab-production-tunnel-pg12/sessions/20652/commands/67783

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #415925 (closed)