sql: deflake TestBackfillWithProtectedTS

We have seen that the DELETE and INSERT step can fail in this test,
which occurs before we manually send the table into the GC queue. To
reduce the chance of this happening, we use a longer gc.ttl.

Release note: None

pkg/sql/backfill_protected_timestamp_test.go

@@ -397,10 +397,10 @@ func TestBackfillWithProtectedTS(t *testing.T) {
 		t.Run(tc.name, func(t *testing.T) {
 			for _, sql := range []string{
 				"SET CLUSTER SETTING sql.stats.automatic_collection.enabled = false",
-				"ALTER DATABASE defaultdb CONFIGURE ZONE USING gc.ttlseconds = 1",
+				"ALTER DATABASE defaultdb CONFIGURE ZONE USING gc.ttlseconds = 5",
 				"DROP TABLE IF EXISTS t CASCADE",
 				"CREATE TABLE t(n int)",
-				"ALTER TABLE t CONFIGURE ZONE USING range_min_bytes = 0, range_max_bytes = 67108864, gc.ttlseconds = 1",
+				"ALTER TABLE t CONFIGURE ZONE USING range_min_bytes = 0, range_max_bytes = 67108864, gc.ttlseconds = 5",
 				fmt.Sprintf("INSERT INTO t(n) SELECT * FROM generate_series(1, %d)", initialRowCount),
 			} {
 				r.Exec(t, sql)