mgr/dashboards: Regenerate protos.

cd src/pybind/mgr
python -m grpc_tools.protoc --proto_path=. --python_out=. --grpc_python_out=. dashboard/services/proto/gateway.proto

7: ============================= test session starts ==============================
7: platform linux -- Python 3.12.7, pytest-8.3.3, pluggy-1.5.0
7: cachedir: .tox/py3/.pytest_cache
7: rootdir: /ceph/src/pybind/mgr/dashboard
7: configfile: tox.ini
7: plugins: pyfakefs-5.3.3, instafail-0.5.0, cov-6.0.0
7: ____________________ ERROR collecting controllers/nvmeof.py ____________________
7: controllers/nvmeof.py:24: in <module>
7:     from ..services.nvmeof_client import NVMeoFClient, empty_response, \
7: services/nvmeof_client.py:16: in <module>
7:     from .proto import gateway_pb2 as pb2
7: services/proto/gateway_pb2.py:33: in <module>
7:     _descriptor.EnumValueDescriptor(
7: .tox/py3/lib64/python3.12/site-packages/google/protobuf/descriptor.py:920: in __new__
7:     _message.Message._CheckCalledFromGeneratedFile()
7: E   TypeError: Descriptors cannot be created directly.
7: E   If this call came from a _pb2.py file, your generated code is out of date and must be regenerated with protoc >= 3.19.0.
7: E   If you cannot immediately regenerate your protos, some other possible workarounds are:
7: E    1. Downgrade the protobuf package to 3.20.x or lower.
7: E    2. Set PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION=python (but this will use pure-Python parsing and will be much slower).
7: E
7: E   More information: https://developers.google.com/protocol-buffers/docs/news/2022-05-06#python-updates

Signed-off-by: Paulo E. Castro <[email protected]>