Remove unused constant variables

Breaks Chromium build.

gfe-relnote: n/a (removing unused code)
PiperOrigin-RevId: 290169623
Change-Id: Iaba7390851b8b258f803123405be90a93a715d48

quic/core/congestion_control/bbr_sender.cc

diff --git a/quic/core/congestion_control/bbr_sender.cc b/quic/core/congestion_control/bbr_sender.cc
index e0be6b2..e0ea89c 100644
--- a/quic/core/congestion_control/bbr_sender.cc
+++ b/quic/core/congestion_control/bbr_sender.cc
@@ -53,12 +53,6 @@
 // will exit the STARTUP mode.
 const float kStartupGrowthTarget = 1.25;
 const QuicRoundTripCount kRoundTripsWithoutGrowthBeforeExitingStartup = 3;
-// Coefficient of target congestion window to use when basing PROBE_RTT on BDP.
-const float kModerateProbeRttMultiplier = 0.75;
-// Coefficient to determine if a new RTT is sufficiently similar to min_rtt that
-// we don't need to enter PROBE_RTT.
-const float kSimilarMinRttThreshold = 1.125;
-
 }  // namespace
 
 BbrSender::DebugState::DebugState(const BbrSender& sender)