first_frame_max_size in an ExecuteRequest should be an int32 in protobuf definitions.

In the protobuf definition for ExecuteRequest, the first_frame_max_size parameter is typed as an uint64. See https://github.com/apache/calcite/blob/master/avatica/core/src/main/protobuf/requests.proto#L130. For consistency, it should be an int32.

Similar parameters relating to the frame size are all typed as int32.

For a PrepareAndExecuteRequest, first_frame_max_size is a{{int32}}: https://github.com/apache/calcite/blob/master/avatica/core/src/main/protobuf/requests.proto#L78

For a FetchRequest, frame_max_size is a int32: https://github.com/apache/calcite/blob/master/avatica/core/src/main/protobuf/requests.proto#L96