udp: log when BPF is not attempted (#16304)
udp: log when BPF is not attempted (#16304)

Adding an informative log since I ended up confused when trying to sort out #15845 and needed to fix #15926 accordingly.

Risk Level: n/a (adding info log)
Testing: manual
Signed-off-by: Alyssa Wilk <b9253d1ec9cc3e9d2aab68d288ba3dab3452adf6@chromium.org>
envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,lyft/envoy,lyft/envoy,lyft/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,lyft/envoy,envoyproxy/envoy,envoyproxy/envoy,lyft/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,lyft/envoy