RocksDB: Do not test bogus parameter slave_gtid_info

This removes the test combination
rocksdb_rpl.mdev12179 'innodb,row,row-write-committed-slave-gtid-optimized'
for which the server failed to start due to the invalid parameter
slave_gtid_info=optimized.

This was broken in 5173e396

storage/rocksdb/mysql-test/rocksdb_rpl/combinations

@@ -5,8 +5,3 @@ rocksdb_write_policy=write_committed
 [row-write-prepared]
 binlog-format=row
 rocksdb_write_policy=write_prepared
-
-[row-write-committed-slave-gtid-optimized]
-binlog-format=row
-rocksdb_write_policy=write_committed
-slave_gtid_info=optimized