Add flag count macro for quic_enable_tls_resumption

PiperOrigin-RevId: 311237264
Change-Id: Ia60565e8a73d8dc062670484f6a511d1cde1ec50

quic/core/tls_server_handshaker.cc

diff --git a/quic/core/tls_server_handshaker.cc b/quic/core/tls_server_handshaker.cc
index c8fbda5..5bd5b3d 100644
--- a/quic/core/tls_server_handshaker.cc
+++ b/quic/core/tls_server_handshaker.cc
@@ -475,6 +475,7 @@
   memcpy(out, decrypted_session_ticket_.data(),
          decrypted_session_ticket_.size());
   *out_len = decrypted_session_ticket_.size();
+  QUIC_RELOADABLE_FLAG_COUNT(quic_enable_tls_resumption);
 
   return ssl_ticket_aead_success;
 }