Drop `start_date_sourcing_milestone_id` From Vulnerabilities

What does this MR do and why?

start_date_sourcing_milestone_id is an ignored column (source)

This MR drops the column for step 2 of the 3-MR drop column process

Check for indexes or constraints

Using the command \d+ vulnerabilities on postgres.ai indicates there ARE indexes and constraints

index	fk constraint

migration output

bundle exec rails db:migrate output

~/gitlab-development-kit/gitlab$ bundle exec rails db:migrate 
main: == [advisory_lock_connection] object_id: 182840, pg_backend_pid: 887818
main: == 20231218121131 RemoveStartDateSourcingMilestoneIdColumnFromVulnerabilities: migrating 
main: -- transaction_open?(nil)
main:    -> 0.0000s
main: -- remove_column(:vulnerabilities, :start_date_sourcing_milestone_id)
main:    -> 0.0158s
main: == 20231218121131 RemoveStartDateSourcingMilestoneIdColumnFromVulnerabilities: migrated (0.0245s) 

main: == [advisory_lock_connection] object_id: 182840, pg_backend_pid: 887818
ci: == [advisory_lock_connection] object_id: 183100, pg_backend_pid: 887820
ci: == 20231218121131 RemoveStartDateSourcingMilestoneIdColumnFromVulnerabilities: migrating 
ci: -- transaction_open?(nil)
ci:    -> 0.0000s
ci: -- remove_column(:vulnerabilities, :start_date_sourcing_milestone_id)
ci:    -> 0.0031s
ci: == 20231218121131 RemoveStartDateSourcingMilestoneIdColumnFromVulnerabilities: migrated (0.0110s) 

ci: == [advisory_lock_connection] object_id: 183100, pg_backend_pid: 887820

bundle exec rails db:rollback:main output

~/gitlab-development-kit/gitlab$ bundle exec rails db:rollback:main
main: == [advisory_lock_connection] object_id: 182560, pg_backend_pid: 891165
main: == 20231218121131 RemoveStartDateSourcingMilestoneIdColumnFromVulnerabilities: reverting 
main: -- column_exists?(:vulnerabilities, :start_date_sourcing_milestone_id)
main:    -> 0.0131s
main: -- add_column(:vulnerabilities, :start_date_sourcing_milestone_id, :bigint)
main:    -> 0.0008s
main: -- transaction_open?(nil)
main:    -> 0.0000s
main: -- view_exists?(:postgres_partitions)
main:    -> 0.0005s
main: -- index_exists?(:vulnerabilities, :start_date_sourcing_milestone_id, {:algorithm=>:concurrently})
main:    -> 0.0086s
main: -- execute("SET statement_timeout TO 0")
main:    -> 0.0002s
main: -- add_index(:vulnerabilities, :start_date_sourcing_milestone_id, {:algorithm=>:concurrently})
main:    -> 0.0030s
main: -- execute("RESET statement_timeout")
main:    -> 0.0003s
main: -- index_name(:vulnerabilities, :start_date_sourcing_milestone_id)
main:    -> 0.0000s
main: -- transaction_open?(nil)
main:    -> 0.0000s
main: -- transaction_open?(nil)
main:    -> 0.0000s
main: -- execute("ALTER TABLE vulnerabilities ADD CONSTRAINT fk_88b4d546ef FOREIGN KEY (start_date_sourcing_milestone_id) REFERENCES milestones (id) ON DELETE SET NULL NOT VALID;")
main:    -> 0.0014s
main: -- execute("ALTER TABLE vulnerabilities VALIDATE CONSTRAINT fk_88b4d546ef;")
main:    -> 0.0017s
main: == 20231218121131 RemoveStartDateSourcingMilestoneIdColumnFromVulnerabilities: reverted (0.0566s) 

main: == [advisory_lock_connection] object_id: 182560, pg_backend_pid: 891165

bundle exec rails db:rollback:ci output

~/gitlab-development-kit/gitlab$ bundle exec rails db:rollback:ci
ci: == [advisory_lock_connection] object_id: 182560, pg_backend_pid: 890447
ci: == 20231218121131 RemoveStartDateSourcingMilestoneIdColumnFromVulnerabilities: reverting 
ci: -- column_exists?(:vulnerabilities, :start_date_sourcing_milestone_id)
ci:    -> 0.0223s
ci: -- add_column(:vulnerabilities, :start_date_sourcing_milestone_id, :bigint)
ci:    -> 0.0009s
ci: -- transaction_open?(nil)
ci:    -> 0.0000s
ci: -- view_exists?(:postgres_partitions)
ci:    -> 0.0007s
ci: -- index_exists?(:vulnerabilities, :start_date_sourcing_milestone_id, {:algorithm=>:concurrently})
ci:    -> 0.0079s
ci: -- execute("SET statement_timeout TO 0")
ci:    -> 0.0002s
ci: -- add_index(:vulnerabilities, :start_date_sourcing_milestone_id, {:algorithm=>:concurrently})
ci:    -> 0.0010s
ci: -- execute("RESET statement_timeout")
ci:    -> 0.0002s
ci: -- index_name(:vulnerabilities, :start_date_sourcing_milestone_id)
ci:    -> 0.0000s
ci: -- transaction_open?(nil)
ci:    -> 0.0000s
ci: -- transaction_open?(nil)
ci:    -> 0.0000s
ci: -- execute("ALTER TABLE vulnerabilities ADD CONSTRAINT fk_88b4d546ef FOREIGN KEY (start_date_sourcing_milestone_id) REFERENCES milestones (id) ON DELETE SET NULL NOT VALID;")
ci:    -> 0.0018s
ci: -- execute("ALTER TABLE vulnerabilities VALIDATE CONSTRAINT fk_88b4d546ef;")
ci:    -> 0.0059s
ci: == 20231218121131 RemoveStartDateSourcingMilestoneIdColumnFromVulnerabilities: reverted (0.0806s) 

ci: == [advisory_lock_connection] object_id: 182560, pg_backend_pid: 890447

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 #268154 (closed)