quic: turn off GRO (#19088)
quic: turn off GRO (#19088)

Signed-off-by: 654382b5c2e21ef54f49ac74d0e9fa1b331b2d46@google.com

Commit Message: hard code prefer_gro to false. The performance of GRO hasn't been evaluated yet, so it shouldn't be default on.

Risk Level: low
Testing: existing tests pass
envoyproxy/envoy,lyft/envoy,lyft/envoy,envoyproxy/envoy,envoyproxy/envoy,lyft/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,lyft/envoy,lyft/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,lyft/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy