Bouncer: Change color of emergency button

Change color of the emergency button to 'colorAccentTertiary'.

Bug: 223224098
Test: Manual on device
Change-Id: Ic853b9d48ac933d2d7265bd1b63a72adc0294401

packages/SystemUI/res-keyguard/drawable/kg_emergency_button_background.xml

@@ -15,10 +15,11 @@
   ~ limitations under the License.
   -->
 <ripple xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:androidprv="http://schemas.android.com/apk/prv/res/android"
     android:color="?attr/wallpaperTextColorSecondary">
     <item android:id="@android:id/background">
         <shape android:shape="rectangle">
-            <solid android:color="?android:attr/colorAccent"/>
+            <solid android:color="?androidprv:attr/colorAccentTertiary"/>
             <corners android:radius="24dp"/>
         </shape>
     </item>