remove DB_TYPE_ROCKSDB

sql/handler.h

@@ -434,8 +434,7 @@ enum legacy_db_type
   DB_TYPE_PERFORMANCE_SCHEMA=28,
   DB_TYPE_ARIA=42,
   DB_TYPE_TOKUDB=43,
-  DB_TYPE_ROCKSDB=44,
-  DB_TYPE_FIRST_DYNAMIC=45,
+  DB_TYPE_FIRST_DYNAMIC=44,
   DB_TYPE_DEFAULT=127 // Must be last
 };
 /*

storage/rocksdb/ha_rocksdb.cc

@@ -3304,7 +3304,6 @@ static int rocksdb_init_func(void *const p) {
   rocksdb_hton->recover = rocksdb_recover;
   rocksdb_hton->commit = rocksdb_commit;
   rocksdb_hton->rollback = rocksdb_rollback;
-  rocksdb_hton->db_type = DB_TYPE_ROCKSDB;
   rocksdb_hton->show_status = rocksdb_show_status;
   rocksdb_hton->start_consistent_snapshot =
       rocksdb_start_tx_and_assign_read_view;