chore: add custom_services and booking_custom_services to test DB cleanup lists

Add custom_services and booking_custom_services to testdb dropOrder and TruncateTables lists, and add CreateTestCustomService/DeleteCustomService fixture helpers.

Ultraworked with Sisyphus (https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

backend/testutils/testdb/testdb.go

@@ -113,6 +113,7 @@ func Migrate(t *testing.T, pool *pgxpool.Pool) {
 			"admin_notifications",
 			"user_notification_preferences",
 			"user_referrals",
+			"booking_custom_services",
 			"booking_services",
 			"refunds",
 			"payments",
@@ -127,6 +128,7 @@ func Migrate(t *testing.T, pool *pgxpool.Pool) {
 			"patch_tests",
 			"booking_edit_requests",
 			"services",
+			"custom_services",
 			"verification_codes",
 			"user_social_logins",
 			"users",
@@ -282,6 +284,7 @@ func TruncateTables(t *testing.T, pool *pgxpool.Pool) {
 		"forgiven_no_shows",
 		"user_social_logins",
 		"verification_codes",
+		"booking_custom_services",
 		"booking_services",
 		"refunds",
 		"payments",
@@ -296,6 +299,7 @@ func TruncateTables(t *testing.T, pool *pgxpool.Pool) {
 		"user_patch_tests",
 		"patch_tests",
 		"services",
+		"custom_services",
 		"admin_notifications",
 		"user_referrals",
 		"user_notification_preferences",