Remove tmp index used for data migration

Removes tmp_index_merge_requests_draft_and_status_leaky_regex

Changelog: removed

db/migrate/20220422220507_remove_tmp_index_supporting_leaky_regex_cleanup.rb

+# frozen_string_literal: true
+
+class RemoveTmpIndexSupportingLeakyRegexCleanup < Gitlab::Database::Migration[2.0]
+  INDEX_NAME = "tmp_index_merge_requests_draft_and_status_leaky_regex"
+  LEAKY_REGEXP_STR = "^\\[draft\\]|\\(draft\\)|draft:|draft|\\[WIP\\]|WIP:|WIP"
+  CORRECTED_REGEXP_STR = "^(\\[draft\\]|\\(draft\\)|draft:|draft|\\[WIP\\]|WIP:|WIP)"
+
+  disable_ddl_transaction!
+
+  def up
+    remove_concurrent_index_by_name :merge_requests, INDEX_NAME
+  end
+
+  def down
+    where_clause = <<~SQL
+      draft = true AND
+      state_id = 1 AND
+      ((title)::text ~* '#{LEAKY_REGEXP_STR}'::text) AND ((title)::text !~* '#{CORRECTED_REGEXP_STR}'::text)
+    SQL
+
+    add_concurrent_index :merge_requests, :id,
+      where: where_clause,
+      name: INDEX_NAME
+  end
+end

db/schema_migrations/20220422220507

+4042ca84ca23fafa3943705704c68606f1c423832395170d93988f90255c3249
\ No newline at end of file

db/structure.sql

@@ -29725,8 +29725,6 @@ CREATE INDEX tmp_index_issues_on_issue_type_and_id ON issues USING btree (issue_
 CREATE INDEX tmp_index_members_on_state ON members USING btree (state) WHERE (state = 2);
-CREATE INDEX tmp_index_merge_requests_draft_and_status_leaky_regex ON merge_requests USING btree (id) WHERE ((draft = true) AND (state_id = 1) AND ((title)::text ~* '^\[draft\]|\(draft\)|draft:|draft|\[WIP\]|WIP:|WIP'::text) AND ((title)::text !~* '^(\[draft\]|\(draft\)|draft:|draft|\[WIP\]|WIP:|WIP)'::text));
-
 CREATE INDEX tmp_index_namespaces_empty_traversal_ids_with_child_namespaces ON namespaces USING btree (id) WHERE ((parent_id IS NOT NULL) AND (traversal_ids = '{}'::integer[]));
 CREATE INDEX tmp_index_namespaces_empty_traversal_ids_with_root_namespaces ON namespaces USING btree (id) WHERE ((parent_id IS NULL) AND (traversal_ids = '{}'::integer[]));