Use new settings preference theme in sysui tuner

- Also removed deprecated activity manifest entry for tuneractivity

Change-Id: Id3a8d25cd9e2bf18c999e273714a2b82fd14ffe8
Fix: 36663882
Test: visual
diff --git a/packages/SystemUI/res/values/styles.xml b/packages/SystemUI/res/values/styles.xml
index e375a21..e9dd7e6 100644
--- a/packages/SystemUI/res/values/styles.xml
+++ b/packages/SystemUI/res/values/styles.xml
@@ -435,8 +435,7 @@
         <item name="preferenceTheme">@style/TunerPreferenceTheme</item>
     </style>
 
-    <style name="TunerPreferenceTheme" parent="@android:style/Theme.DeviceDefault.Settings">
-        <item name="dropdownPreferenceStyle">@style/Preference.DropDown.Material</item>
+    <style name="TunerPreferenceTheme" parent="@style/PreferenceThemeOverlay.SettingsBase">
     </style>
 
     <style name="TextAppearance.NotificationInfo">