Drop index_deployments_on_project_id_and_status

What does this MR do and why?

This is part of an epic to optimize the deployments table by dropping unused indexes: &10185

MR to drop the index in production asynchronously: !125250 (merged)

Issue: #403595 (closed)

Screenshots or screen recordings

Migration output

main: == [advisory_lock_connection] object_id: 223740, pg_backend_pid: 13484
main: == 20230712052619 DropIndexDeploymentsOnProjectIdAndStatus: migrating =========
main: -- transaction_open?()
main:    -> 0.0000s
main: -- view_exists?(:postgres_partitions)
main:    -> 0.0839s
main: -- indexes(:deployments)
main:    -> 0.0085s
main: -- execute("SET statement_timeout TO 0")
main:    -> 0.0005s
main: -- remove_index(:deployments, {:algorithm=>:concurrently, :name=>"index_deployments_on_project_id_and_status"})
main:    -> 0.0033s
main: -- execute("RESET statement_timeout")
main:    -> 0.0003s
main: == 20230712052619 DropIndexDeploymentsOnProjectIdAndStatus: migrated (0.1228s) 

main: == [advisory_lock_connection] object_id: 223740, pg_backend_pid: 13484

Check index existence on production DB

How to set up and validate locally

N/A

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 #403595 (closed)