Update list of nonconforming tests

Summary:
https://fb.workplace.com/groups/thriftusers/permalink/1558321331543940/

These tests actually were conforming and shouldn't have been marked as non-conforming.

Reviewed By: dtolnay

Differential Revision: D68787968

fbshipit-source-id: 424a2059028a54dbdfbf373d8814d71f49964787

Author: slawlor

thrift/conformance/data/nonconforming.txt

@@ -17885,8 +17885,6 @@ rust/ThriftRPCClientTest/StreamCreditTimeout/Success.StreamCreditTimeoutTest
 rust/ThriftRPCClientTest/StreamInitialTimeout/Success.StreamInitialTimeoutTest
 
 # These are unable to be implemented due to missing Rust functionality
-rust/ThriftRPCClientTest/StreamFragmentation/Success.StreamFragmentationTest
-rust/ThriftRPCClientTest/StreamSubsequentCredits/Success.StreamSubsequentCreditsTest
 rust/ThriftRPCClientTest/SinkBasic/Success.SinkBasicTest
 rust/ThriftRPCClientTest/SinkFragmentation/Success.SinkFragmentationTest
 rust/ThriftRPCClientTest/SinkSubsequestCredits/Success.SinkSubsequentCreditsTest