x/bank/keeper: fix a missing gRPC error in AllBalances

Fixes an incoherent return which had:
    (non-nil value, non-nil-non-grpc error)
to
    (nil value, non-nil-gRPC error)

and it is a follow-up of PR #7814.

x/bank/keeper/grpc_query.go

@@ -72,7 +72,7 @@ func (k BaseKeeper) AllBalances(ctx context.Context, req *types.QueryAllBalances
 	})
 
 	if err != nil {
-		return &types.QueryAllBalancesResponse{}, err
+		return nil, status.Errorf(codes.InvalidArgument, "paginate: %v", err)
 	}
 
 	return &types.QueryAllBalancesResponse{Balances: balances, Pagination: pageRes}, nil