Add post_deploy migration for drop

Added the post deploy migration for
dropping the column

db/post_migrate/20220325050642_drop_integrations_template_column.rb

+# frozen_string_literal: true
+
+class DropIntegrationsTemplateColumn < Gitlab::Database::Migration[1.0]
+  enable_lock_retries!
+
+  def change
+    remove_column :integrations, :template, :boolean, default: false
+  end
+end

db/schema_migrations/20220325050642

+9ce5b7640c5d0c0e7cab0d12600b8378efb6a68922a361b0bee5617a69c3ee53
\ No newline at end of file

db/structure.sql

@@ -16101,7 +16101,6 @@ CREATE TABLE integrations (
     confidential_note_events boolean DEFAULT true,
     deployment_events boolean DEFAULT false NOT NULL,
     comment_on_event_enabled boolean DEFAULT true NOT NULL,
-    template boolean DEFAULT false,
     instance boolean DEFAULT false NOT NULL,
     comment_detail smallint,
     inherit_from_id bigint,
@@ -27862,22 +27861,16 @@ CREATE UNIQUE INDEX index_integrations_on_project_id_and_type_new_unique ON inte
 
 CREATE UNIQUE INDEX index_integrations_on_project_id_and_type_unique ON integrations USING btree (project_id, type);
 
-CREATE INDEX index_integrations_on_template ON integrations USING btree (template);
-
 CREATE INDEX index_integrations_on_type ON integrations USING btree (type);
 
 CREATE UNIQUE INDEX index_integrations_on_type_and_instance_partial ON integrations USING btree (type, instance) WHERE (instance = true);
 
-CREATE UNIQUE INDEX index_integrations_on_type_and_template_partial ON integrations USING btree (type, template) WHERE (template = true);
-
 CREATE INDEX index_integrations_on_type_id_when_active_and_project_id_not_nu ON integrations USING btree (type, id) WHERE ((active = true) AND (project_id IS NOT NULL));
 
 CREATE INDEX index_integrations_on_type_new ON integrations USING btree (type_new);
 
 CREATE INDEX index_integrations_on_type_new_and_instance_partial ON integrations USING btree (type_new, instance) WHERE (instance = true);
 
-CREATE INDEX index_integrations_on_type_new_and_template_partial ON integrations USING btree (type_new, template) WHERE (template = true);
-
 CREATE INDEX index_integrations_on_type_new_id_when_active_and_has_project ON integrations USING btree (type_new, id) WHERE ((active = true) AND (project_id IS NOT NULL));
 
 CREATE UNIQUE INDEX index_integrations_on_unique_group_id_and_type ON integrations USING btree (group_id, type);