bazel: Remove deps that protobuf includes
bazel: Remove deps that protobuf includes

net_zlib is no longer used ("zlib" is used instead). Zlib and skylib are
both included via protobuf_deps(). With the language-specific rules
needing to be imported (e.g., rules_proto, rules_java) we are relying on
protobuf_deps() pretty heavily starting in Protobuf 3.10, so we aren't
losing much to remove these two deps.

grpc/grpc-java,grpc/grpc-java,ejona86/grpc-java,dapengzhang0/grpc-java,dapengzhang0/grpc-java,ejona86/grpc-java,ejona86/grpc-java,stanley-cheung/grpc-java,dapengzhang0/grpc-java,dapengzhang0/grpc-java,stanley-cheung/grpc-java,stanley-cheung/grpc-java,ejona86/grpc-java,grpc/grpc-java,stanley-cheung/grpc-java,grpc/grpc-java