Add `first` & `latest` pipeline IDs to `vulnerability_occurrences`

We want to drop the `vulnerability_occurrence_pipelines` table. In
order to do this, we still need the first and latest pipeline ID
stored somewhere to support the existing feature-set

These columns should both be nullable, as continuous scanning or
alternative scan sources will not have a pipeline_id to associate.

resolves: #422382

Changelog: added

db/migrate/20240214035028_add_first_and_latest_pipeline_id_to_vulnerability_occurrences.rb

+# frozen_string_literal: true
+
+class AddFirstAndLatestPipelineIdToVulnerabilityOccurrences < Gitlab::Database::Migration[2.2]
+  # When using the methods "add_concurrent_index" or "remove_concurrent_index"
+  # you must disable the use of transactions
+  # as these methods can not run in an existing transaction.
+  # When using "add_concurrent_index" or "remove_concurrent_index" methods make sure
+  # that either of them is the _only_ method called in the migration,
+  # any other changes should go in a separate migration.
+  # This ensures that upon failure _only_ the index creation or removing fails
+  # and can be retried or reverted easily.
+  #
+  # To disable transactions uncomment the following line and remove these
+  # comments:
+  # disable_ddl_transaction!
+  #
+  # Configure the `gitlab_schema` to perform data manipulation (DML).
+  # Visit: https://docs.gitlab.com/ee/development/database/migrations_for_multiple_databases.html
+  # restrict_gitlab_migration gitlab_schema: :gitlab_main
+  milestone '16.10'
+
+  def change
+    add_column :vulnerability_occurrences, :first_pipeline_id, :bigint, null: true
+    add_column :vulnerability_occurrences, :latest_pipeline_id, :bigint, null: true
+  end
+end

db/schema_migrations/20240214035028

+3c817aa6647e70b9888da3b4c044bd1b63f3bfeb5a47d85debe1350675088499
\ No newline at end of file

db/structure.sql

@@ -17291,6 +17291,8 @@ CREATE TABLE vulnerability_occurrences (
     location jsonb,
     detection_method smallint DEFAULT 0 NOT NULL,
     uuid uuid DEFAULT '00000000-0000-0000-0000-000000000000'::uuid NOT NULL,
+    first_pipeline_id bigint,
+    latest_pipeline_id bigint,
     CONSTRAINT check_4a3a60f2ba CHECK ((char_length(solution) <= 7000)),
     CONSTRAINT check_ade261da6b CHECK ((char_length(description) <= 15000)),
     CONSTRAINT check_f602da68dd CHECK ((char_length(cve) <= 48400))