add OLM scaling for max_connection_duration (#36816)

add OLM scaling for max_connection_duration

This allows for configuring scaling the max connection duration in
response to overload.

Risk Level: low
Testing: integration & unit tests
Docs Changes: none
Release Notes: in changelog

---------

Signed-off-by: antoniovleonti <leonti@google.com>

Mirrored from https://github.com/envoyproxy/envoy @ ae4391145fb38487a3206e7b77c402d928857e7b

envoy/config/overload/v3/overload.proto

@@ -103,6 +103,12 @@ message ScaleTimersOverloadActionConfig {
     // This affects the value of
     // :ref:`FilterChain.transport_socket_connect_timeout <envoy_v3_api_field_config.listener.v3.FilterChain.transport_socket_connect_timeout>`.
     TRANSPORT_SOCKET_CONNECT = 3;
+
+    // Adjusts the max connection duration timer for downstream HTTP connections.
+    // This affects the value of
+    // :ref:`HttpConnectionManager.common_http_protocol_options.max_connection_duration
+    // <envoy_v3_api_field_config.core.v3.HttpProtocolOptions.max_connection_duration>`.
+    HTTP_DOWNSTREAM_CONNECTION_MAX = 4;
   }
 
   message ScaleTimer {