Ratelimit Per Route Limit Override

The HTTP :ref:rate limit filter <config_http_filters_rate_limit> now supports the :ref:limit <envoy_v3_api_field_config.route.v3.RateLimit.limit> override (including the dynamic_metadata source) when the rate limit configuration is supplied via the filter's rate_limits field or the per-route :ref:RateLimitPerRoute <envoy_v3_api_msg_extensions.filters.http.ratelimit.v3.RateLimitPerRoute>. This allows the per-descriptor limit override and the per-request :ref:hits_addend <envoy_v3_api_field_config.route.v3.RateLimit.hits_addend> to be used together on the same rule.