Fix mixing rules from builtins and protobuf

The rules in protobuf and built-in Bazel don't mix well. Different aspects may cause actions conflicts. The safest way is to use built-in rules whenever they are still present.

proto_library should be safe, because it's not using an aspect. py_proto_library never had a built-in implementation, so it's also safe.

This still makes it possible to use the rules on Bazel 7, but only with --incompatible_autoload_externally enabled.

PiperOrigin-RevId: 678446311