Update interops test proto to match grpc-java.

[creamsoup]

The test.proto is adapted from grpc-java, and stubby4 server for cloud to cloud
interops test gets same update.

• Using protobuf provided BoolValue instead of custom one.
  the issue in the command is closed, and interops test passed
• This change is backward compatible.

[carl-mastrangelo]

be careful here, have you checked the other languages in grpc/grpc and grpc/grpc-go can make this change?

[ejona86]

I'd feel much better if we delayed making the wrappers change until after the various languages were all pulling from the same proto. We've had trouble with the well-known protos in a few languages, since our build infrastructure is... weird... in places.

[ejona86]

My statement applies to Empty as well.

[creamsoup]

changed back to use custom message types. I tested the previous version in go / c++ / python / ruby, etc. the well-known protos seem to work fine. but i agree that it still seems wiser to sync between languages first.

[creamsoup]

for the BoolValue, grpc-java actually uses well known protos. Since we want to keep the custom one due to the past issue, changing the java one to use custom bool value.

[ejona86]

grpc-java using BoolValue for the moment sounds fine.