Remove unique index

- Remove unique index

Changelog: removed
MR: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/79683

db/migrate/20220201205300_remove_index_for_vulnerability_occurrences.rb

+# frozen_string_literal: true
+
+class RemoveIndexForVulnerabilityOccurrences < Gitlab::Database::Migration[1.0]
+  INDEX_NAME = 'index_vulnerability_occurrences_on_unique_keys'
+
+  disable_ddl_transaction!
+
+  def up
+    remove_concurrent_index_by_name :vulnerability_occurrences, INDEX_NAME
+  end
+
+  def down
+    # no-op
+
+    # The index is UNIQUE so we cannot add it back again
+  end
+end

db/schema_migrations/20220201205300

+79a636f33f70327206356abd1793b73a5ef5e920a41662e35cbff5597b03a365
\ No newline at end of file

db/structure.sql

@@ -28177,8 +28177,6 @@ CREATE INDEX index_vulnerability_occurrences_on_project_fingerprint ON vulnerabi
 
 CREATE INDEX index_vulnerability_occurrences_on_scanner_id ON vulnerability_occurrences USING btree (scanner_id);
 
-CREATE UNIQUE INDEX index_vulnerability_occurrences_on_unique_keys ON vulnerability_occurrences USING btree (project_id, primary_identifier_id, location_fingerprint, scanner_id);
-
 CREATE UNIQUE INDEX index_vulnerability_occurrences_on_uuid ON vulnerability_occurrences USING btree (uuid);
 
 CREATE INDEX index_vulnerability_occurrences_on_vulnerability_id ON vulnerability_occurrences USING btree (vulnerability_id);