Code review comment: I think we can remove the DEFAULT_CLUSTER also. The feature is useless but only has compatibility.

Code under review:
public TGetDBPrivsResult getDBPrivs(TGetDBPrivsParams params) throws TException {
        LOG.debug("get database privileges request: {}", params);
        TGetDBPrivsResult result = new TGetDBPrivsResult();
        List<TDBPrivDesc> tDBPrivs = Lists.newArrayList();
        result.setDb_privs(tDBPrivs);
        UserIdentity currentUser = UserIdentity.fromThrift(params.current_user_ident);
        List<DbPrivEntry> dbPrivEntries = GlobalStateMgr.getCurrentState().getAuth().getDBPrivEntries(currentUser);
        
        for (DbPrivEntry entry : dbPrivEntries) {
            PrivBitSet savedPrivs = entry.getPrivSet();
            String clusterPrefix = SystemInfoService.DEFAULT_CLUSTER + ClusterNamespace.CLUSTER_DELIMITER;
            String userIdentStr = currentUser.toString().replace(clusterPrefix, "");
            String dbName = entry.getOrigDb();
            boolean isGrantable = savedPrivs.satisfy(PrivPredicate.GRANT);
            List<TDBPrivDesc> tPrivs = savedPrivs.toPrivilegeList().stream().map(
                    priv -> {
                        TDBPrivDesc privDesc = new TDBPrivDesc();
                        privDesc.setDb_name(dbName);
                        privDesc.setIs_grantable(isGrantable);
                        privDesc.setUser_ident_str(userIdentStr);
                        privDesc.setPriv(priv.getUpperNameForMysql());
                        return privDesc;
                    }
            ).collect(Collectors.toList());
            if (savedPrivs.satisfy(PrivPredicate.LOAD)) {
                
                tPrivs.addAll(Lists.newArrayList("INSERT", "UPDATE", "DELETE").stream().map(priv -> {
                    TDBPrivDesc privDesc = new TDBPrivDesc();
                    privDesc.setDb_name(dbName);
                    privDesc.setIs_grantable(isGrantable);
                    privDesc.setUser_ident_str(userIdentStr);
                    privDesc.setPriv(priv);
                    return privDesc;
                }).collect(Collectors.toList()));
            }
            tDBPrivs.addAll(tPrivs);
        }
        return result;
    }

Line commented on: String clusterPrefix = SystemInfoService.DEFAULT_CLUSTER + ClusterNamespace.CLUSTER_DELIMITER;

Revised code:
public TGetDBPrivsResult getDBPrivs(TGetDBPrivsParams params) throws TException {
        LOG.debug("get database privileges request: {}", params);
        TGetDBPrivsResult result = new TGetDBPrivsResult();
        List<TDBPrivDesc> tDBPrivs = Lists.newArrayList();
        result.setDb_privs(tDBPrivs);
        UserIdentity currentUser = UserIdentity.fromThrift(params.current_user_ident);
        List<DbPrivEntry> dbPrivEntries = GlobalStateMgr.getCurrentState().getAuth().getDBPrivEntries(currentUser);
        
        for (DbPrivEntry entry : dbPrivEntries) {
            PrivBitSet savedPrivs = entry.getPrivSet();
            String clusterPrefix = SystemInfoService.DEFAULT_CLUSTER + ClusterNamespace.CLUSTER_DELIMITER;
            String userIdentStr = currentUser.toString().replace(clusterPrefix, "");
            String dbName = entry.getOrigDb();
            boolean isGrantable = savedPrivs.satisfy(PrivPredicate.GRANT);
            List<TDBPrivDesc> tPrivs = savedPrivs.toPrivilegeList().stream().map(
                    priv -> {
                        TDBPrivDesc privDesc = new TDBPrivDesc();
                        privDesc.setDb_name(dbName);
                        privDesc.setIs_grantable(isGrantable);
                        privDesc.setUser_ident_str(userIdentStr);
                        privDesc.setPriv(priv.getUpperNameForMysql());
                        return privDesc;
                    }
            ).collect(Collectors.toList());
            if (savedPrivs.satisfy(PrivPredicate.LOAD)) {
                
                tPrivs.addAll(Lists.newArrayList("INSERT", "UPDATE", "DELETE").stream().map(priv -> {
                    TDBPrivDesc privDesc = new TDBPrivDesc();
                    privDesc.setDb_name(dbName);
                    privDesc.setIs_grantable(isGrantable);
                    privDesc.setUser_ident_str(userIdentStr);
                    privDesc.setPriv(priv);
                    return privDesc;
                }).collect(Collectors.toList()));
            }
            tDBPrivs.addAll(tPrivs);
        }
        return result;
    }