The stubs generated by grpcio_tools should always be used with [the same or higher version of grpcio](https://github.com/grpc/grpc/blob/master/tools/distrib/python/grpcio_tools/setup.py#L313), this change will add a run time check for this requirement inside the generated stubs and therefor enforce this requirement.
Please note for now we're just printing a warning for incorrect usage, we'll **change it to an error** soon.
Example warning message:
```
/usr/local/google/home/xuanwn/workspace/misc/grpc/examples/python/helloworld/helloworld_pb2_grpc.py:21: RuntimeWarning: The grpc package installed is at version 1.60.1, but the generated code in helloworld_pb2_grpc.py depends on grpcio>=1.63.0.dev0. Please upgrade your grpc module to grpcio>=1.63.0.dev0 or downgrade your generated code using grpcio-tools<=1.60.1. This warning will become an error in 1.64.0, scheduled for release on May 14,2024.
```
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Closes#35906
PiperOrigin-RevId: 615659471
To support magical internal build processes, the pb2 files need to be
split into pure-proto and gRPC parts. This performs that split and
further fixes bad module names in the test harness that interfered with
the intended test implementation.
An unfortunate side effect, due to limitations of protoc and holdover
behavior we must support in major version 1.x, is that trash files are
generated in split generation. This shouldn't be a problem in normal
protoc plugin use.
Mike Kruskal