Use shared informers for proxy endpoints and service configs

Use shared informers instead of creating local controllers/reflectors
for the proxy's endpoints and service configs. This allows downstream
integrators to pass in preexisting shared informers to save on memory &
cpu usage.

This also enables the cache mutation detector for kube-proxy for those
presubmit jobs that already turn it on.

cluster/saltbase/salt/kube-proxy/kube-proxy.manifest

@@ -32,6 +32,8 @@
 # test_args should always go last to overwrite prior configuration
 {% set params = log_level + " " + feature_gates + " " + test_args -%}
 
+{% set container_env = "" -%}
+
 # kube-proxy podspec
 apiVersion: v1
 kind: Pod
@@ -60,6 +62,7 @@ spec:
     - /bin/sh
     - -c
     - echo -998 > /proc/$$$/oom_score_adj && kube-proxy {{api_servers_with_port}} {{kubeconfig}} {{cluster_cidr}} --resource-container="" {{params}} 1>>/var/log/kube-proxy.log 2>&1
+    {{container_env}}
     securityContext:
       privileged: true
     volumeMounts: