Fix deprecated code in Cpp2ConnContext

Summary:
Before this change, when building from mac, I got the error complaining about deprecated method being used.

Deprecated here: https://www.internalfb.com/code/fbsource/[1ea5ce7555c142cfe4d975e27c3855e987e49b95]/fbcode/thrift/lib/cpp2/FieldRef.h?lines=147-153

Reviewed By: iahs

Differential Revision: D88436271

fbshipit-source-id: fdccba05ea31438ae0dfbc3150cf96a571869377

Author: vilatto

third-party/thrift/src/thrift/lib/cpp2/server/Cpp2ConnContext.h

@@ -781,7 +781,8 @@ class Cpp2RequestContext : public apache::thrift::server::TConnectionContext {
     if (auto* header = getHeader()) {
       if (const auto& loggingContext = header->loggingContext()) {
         if (const auto attemptIdRef = loggingContext->requestAttemptId();
-            attemptIdRef.is_set()) {
+            apache::thrift::is_non_optional_field_set_manually_or_by_serializer(
+                attemptIdRef)) {
           return *attemptIdRef;
         }
       }