Remove unnecessary member connection_ in QuicTransportSimpleServerSession.
gfe-relnote: unused code. not protected.
PiperOrigin-RevId: 284637154
Change-Id: I2c423381f7e9053cdd7e69d5eb2afc052e616177
QUICHE (QUIC, Http/2, Etc) is Google‘s implementation of QUIC and related protocols. It powers Chromium as well as Google’s QUIC servers and some other projects.