Apply top intro preference in Settings app (1/n)

Based on content in footer, we need to convert some footers
to top info prefernce.

Test: Run robo test and see the screens
Bug: 173087905
Change-Id: Ie62a503481f9d385f5468896fba8f607cb3437d3

res/xml/tether_prefs.xml

@@ -19,12 +19,17 @@
     xmlns:settings="http://schemas.android.com/apk/res-auto"
     android:title="@string/tether_settings_title_all">
 
+    <com.android.settingslib.widget.TopIntroPreference
+        android:key="tether_prefs_top_intro"
+        settings:searchable="false"/>
+
     <com.android.settings.widget.FixedLineSummaryPreference
         android:key="wifi_tether"
         android:title="@string/wifi_hotspot_checkbox_text"
         android:summary="@string/summary_placeholder"
         android:fragment="com.android.settings.wifi.tether.WifiTetherSettings"
-        settings:summaryLineCount="2" />
+        settings:allowDividerAbove="true"
+        settings:summaryLineCount="2"/>
 
     <SwitchPreference
         android:key="usb_tether_settings"
@@ -49,9 +54,4 @@
         android:summary="@string/tether_settings_disabled_on_data_saver"
         android:selectable="false"
         settings:allowDividerAbove="true" />
-
-    <com.android.settingslib.widget.FooterPreference
-        android:key="tether_prefs_footer"
-        android:selectable="false"
-        settings:searchable="false"/>
 </PreferenceScreen>