Overload manager doesn't exclude probes from stop_accepting_* actions

*Title*: *Overload manager should exclude probes from stop_accept_* actions*

*Description*:
We are recently testing overload manager with istio. Our scenario is to overload the ingressgateway heap_size configured via sending requests from large number of concurrent connections, then we see stop_accepting_connections/requests actions triggered and new requests will fail.
But we found stop_accepting_connections(also stop_accepting_requests) stops the internal probes like liveness probe and readiness probe, which leads to the restart of the ingressgateway pod, which will causes issue for us.

We think it's reasonable to exclude the probes like liveness/readiness probe from overload manager stop_accepting_* actions, because new traffic will still fail and return users error 503 to indicate the overload, there seems to be no need to also stop internal probes.

Or we would like to know if it's intentionally to include probes into stop_accepting_* actions, if so, why?

related topic https://github.com/envoyproxy/envoy/issues/21923