http3: changing how http3 is built (#15540)

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Additional Description:
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Testing:
Docs Changes:
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Platform Specific Features:
Much of #12829

Signed-off-by: Alyssa Wilk <alyssar@chromium.org>

Mirrored from https://github.com/envoyproxy/envoy @ b0ce15c96cebd89cf391869e49017325cd7faaa8

envoy/config/listener/v3/quic_config.proto

@@ -16,8 +16,6 @@ option java_multiple_files = true;
 option (udpa.annotations.file_status).package_version_status = ACTIVE;
 
 // [#protodoc-title: QUIC listener config]
-// [#comment:#extension: envoy.udp_listeners.quiche_quic_listener]
-// [#comment:TODO(#12829): Remove this as an extension point.]
 
 // Configuration specific to the UDP QUIC listener.
 message QuicProtocolOptions {

envoy/config/listener/v4alpha/quic_config.proto

@@ -16,8 +16,6 @@ option java_multiple_files = true;
 option (udpa.annotations.file_status).package_version_status = NEXT_MAJOR_VERSION_CANDIDATE;
 
 // [#protodoc-title: QUIC listener config]
-// [#comment:#extension: envoy.udp_listeners.quiche_quic_listener]
-// [#comment:TODO(#12829): Remove this as an extension point.]
 
 // Configuration specific to the UDP QUIC listener.
 message QuicProtocolOptions {