shill: Reduce log noise.

- Print a single message rather that two messages for each
  auto-connect attempt.

- Don't override Service::AutoConnect in WiFiService because it
  doesn't seem to do anything different now.

- No need to log WiFiEndpoint::PropertiesChanged at INFO level.

BUG=none
TEST=tested on device, ran unit tests

Change-Id: I575d06986a067d42ec9d7c717e284e83e12e460c
Reviewed-on: https://gerrit.chromium.org/gerrit/26226
Commit-Ready: Darin Petkov <petkov@chromium.org>
Reviewed-by: Darin Petkov <petkov@chromium.org>
Tested-by: Darin Petkov <petkov@chromium.org>
diff --git a/wifi_endpoint.cc b/wifi_endpoint.cc
index e7450a8..5da0ec3 100644
--- a/wifi_endpoint.cc
+++ b/wifi_endpoint.cc
@@ -76,7 +76,7 @@
 
 void WiFiEndpoint::PropertiesChanged(
     const map<string, ::DBus::Variant> &properties) {
-  LOG(INFO) << __func__;
+  SLOG(WiFi, 2) << __func__;
   map<string, ::DBus::Variant>::const_iterator properties_it =
       properties.find(wpa_supplicant::kBSSPropertySignal);
   if (properties_it != properties.end()) {