Revert aa9478f06d613cd7b845e609a8c20c1ce116dad5 (#4581)

This PR reverts #4382. When deploying at Lyft we noticed crashes on here where we might be derefencing the connection_stats_ pointer after the point has been reset.

Note: this PR keeps the changes to the API made in the original PR but tags the field as not implemented. This is what we have done in the past for reverts that involve changes that change the API.

Signed-off-by: Jose Nino <jnino@lyft.com>

Mirrored from https://github.com/envoyproxy/envoy @ 9d32e5c2a14cd9ab96b6e77fb04f7bd77b2c0d71

envoy/config/filter/network/http_connection_manager/v2/http_connection_manager.proto

@@ -175,6 +175,7 @@ message HttpConnectionManager {
   // option is not specified.
   google.protobuf.Duration drain_timeout = 12 [(gogoproto.stdduration) = true];
 
+  // [#not-implemented-hide:]
   // The delayed close timeout is for downstream connections managed by the HTTP connection manager.
   // It is defined as a grace period after connection close processing has been locally initiated
   // during which Envoy will flush the write buffers for the connection and await the peer to close