fix(admission): use client network, fail-open on nil gRPC client, close http resources

- Use client address network instead of listener network in admission wrapper
- Return true (allow) when gRPC admission plugin client is nil to fail-open
- Add Close() to httpPlugin to close idle HTTP connections
- Close httpLoader in localAdmission.Close()
- Remove dead commented-out code in periodReload

admission/wrapper/listener.go

@@ -47,7 +47,7 @@ func (ln *listener) Accept() (net.Conn, error) {
 		}
 
 		if ln.admission != nil &&
-			!ln.admission.Admit(ctx, ln.Addr().Network(), clientAddr.String(), admission.WithService(ln.service)) {
+			!ln.admission.Admit(ctx, clientAddr.Network(), clientAddr.String(), admission.WithService(ln.service)) {
 			c.Close()
 			continue
 		}