add index on content_tags to make lookup / bulk updating easier

flag=none

Test plan:
 - Already tested: https://instructure.slack.com/archives/C0292K3J1/p1676774757040499

Change-Id: Id9c7f05cf7996d6aaf1c1529d2d95df3a26fcc67
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/311485
Reviewed-by: Jacob Burroughs <jburroughs@instructure.com>
Migration-Review: Jacob Burroughs <jburroughs@instructure.com>
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
QA-Review: Alex Slaughter <aslaughter@instructure.com>
Product-Review: Alex Slaughter <aslaughter@instructure.com>

db/migrate/20230219072741_index_content_tag.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+#
+# Copyright (C) 2023 - present Instructure, Inc.
+#
+# This file is part of Canvas.
+#
+# Canvas is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Affero General Public License as published by the Free
+# Software Foundation, version 3 of the License.
+#
+# Canvas is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along
+# with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+
+class IndexContentTag < ActiveRecord::Migration[6.1]
+  tag :postdeploy
+  disable_ddl_transaction!
+
+  def change
+    add_index :content_tags, %i[content_id content_type url], algorithm: :concurrently, if_not_exists: true
+  end
+end