Add metrics constant for wifi scanning dialog

This CL simply adds a metrics proto constant for the new dialog
that shows up if you try to tunr on auto-wifi without first
enabling wifi scanning.

Test: robotests still pass
Bug: 67070896
Change-Id: I9a4e0fa105e67d666e2e34588bea037034a28784

proto/src/metrics_constants.proto

@@ -5572,6 +5572,12 @@ message MetricsEvent {
     // OS: P
     ACTION_SETTINGS_SLICE_CHANGED = 1372;
 
+    // OPEN: Settings > Network & Internet > Wi-Fi > Wi-Fi Preferences > Turn on Wi-Fi automatically
+    //       note: Wifi Scanning must be off for this dialog to show
+    // CATEGORY: SETTINGS
+    // OS: P
+    WIFI_SCANNING_NEEDED_DIALOG = 1373;
+
     // ---- End P Constants, all P constants go above this line ----
     // Add new aosp constants above this line.
     // END OF AOSP CONSTANTS