ccl/schemachangerccl: deflake TestBackupSuccess

Previously, the backup and restore tests for the declarative schema
changer could flake because the latest completed schema job could not be
sufficiently determined by the finish_time. This was because this time
only has resolution of seconds at most, so multiple jobs could have the
same finish time. To address this, this patch also sorts the jobs by
job_id as well, which should be increasing for later jobs.

Fixes: #131583

Release note: None

pkg/sql/schemachanger/sctest/framework.go

@@ -946,7 +946,7 @@ func waitForSchemaChangesToFinish(t *testing.T, tdb *sqlutils.SQLRunner) {
 
 func hasLatestSchemaChangeSucceeded(t *testing.T, tdb *sqlutils.SQLRunner) bool {
 	result := tdb.QueryStr(t, fmt.Sprintf(
-		`SELECT status FROM [SHOW JOBS] WHERE job_type IN ('%s') ORDER BY finished DESC LIMIT 1`,
+		`SELECT status FROM [SHOW JOBS] WHERE job_type IN ('%s') ORDER BY finished DESC, job_id DESC LIMIT 1`,
 		jobspb.TypeNewSchemaChange,
 	))
 	return result[0][0] == "succeeded"