Fix poolmanager terminates running function pod periodically (#1435)

The pool manager keeps terminating function pod periodically even there are
traffic to the function. The root cause is that executor, poolmgr, newdeploy
manage their own functionServiceCache separately. And when router taps a
function, executor updates the access time of the function service entry in its
own cache without notifying executor types to do the update as well. Hence,
the access time of function service entry in poolmanager cache never gets updated.
Due to the access time never gets updated, the idle pod reaper in poolmanager
then thinks the function pod is in idle state and recycle it.

This PR removes the cache in executor itself, and when router tries to tap a function,
executor will call executor type to tap the function and update access time.

test/tests/test_fn_update/test_idle_objects_reaper.sh

@@ -41,7 +41,7 @@ timeout 60 bash -c "test_fn ${fn}-gpm 'world'"
 log "Waiting for idle pod reaper to recycle resources"
 # the LIST_OLD function list fsvc older than 2 mins
 # so in worst case, we need to wait for up to 4 mins + some buffer
-sleep 260
+sleep 300
 
 # The replicas of function deployment should be 0 due to minScale = 0
 ndDeployReplicas=$(kubectl -n $FUNCTION_NAMESPACE get deploy -l functionName=${fn}-nd -ojsonpath='{.items[0].spec.replicas}')