Device do network scan after user rotates NetworkSelection page

To avoid to do oncreate when device is rotated or the screenSize
changed. Adding the activity's android:configChanges as
"orientation|keyboard|keyboardHidden|screenSize|screenLayout
|smallestScreenSize". (Based on SettingsHomepageActivity's settings
and the smallestScreenSize is for screensize changed on
different display.)

Bug: 204039043
Test: atest AutoSelectPreferenceControllerTest (pass)
atest OpenNetworkSelectPagePreferenceControllerTest (pass)
atest NetworkSelectSettingsTest (pass)

Change-Id: I6aa009fc52a85024a29bf48a3e7d1aadcab067d8
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index 638340e..4967ada 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -191,6 +191,7 @@
         </receiver>
 
         <activity android:name=".SubSettings"
+                  android:configChanges="orientation|keyboard|keyboardHidden|screenSize|screenLayout|smallestScreenSize"
                   android:theme="@style/Theme.SubSettings" />
 
         <activity android:name=".Settings$CreateShortcutActivity"