gfe-relnote: Set first_pto_srtt_multiplier_ to 0.5, just like the PLE1 connection option, when TLPR is present and PTO is enabled in QUIC.  Protected by existing unverified flag quic_arm_pto_with_earliest_sent_time.
gfe-relnote: Set first_pto_srtt_multiplier_ to 0.5, just like the PLE1 connection option, when TLPR is present and PTO is enabled in QUIC.  Protected by existing unverified flag quic_arm_pto_with_earliest_sent_time.

PiperOrigin-RevId: 300630596
Change-Id: I132f97ecd55e7b489c5bbf232010f689993d91fa

google/quiche,google/quiche,google/quiche,google/quiche