Remove tests that are testing on sending only STOP_SENDING. Theses tests use QuicStream::SendStopSending() which is never used in production. Sending and receiving STOP_SENDING is well covered in unit tests. end to end STOP_SENDING communication is covered in end_to_end test such as EndToEndTest.SimpleStopSendingRstStreamTest PiperOrigin-RevId: 328835344 Change-Id: I7a9f07e3582cb9412bf7a86239a4188d335d9504