Set collapsing toolbar background color

-Set collapsing toolbar background as transparent.
-Let header and preference contain use the same background.

Bug: 230230017
Test: manual test
Change-Id: I3152d93b2ac34d73c2f877e719ea3c865a7ce58b

packages/SettingsLib/CollapsingToolbarBaseActivity/res/layout-v31/collapsing_toolbar_content_layout.xml

@@ -25,7 +25,7 @@
         android:fitsSystemWindows="true"
         android:outlineAmbientShadowColor="@android:color/transparent"
         android:outlineSpotShadowColor="@android:color/transparent"
-        android:background="?android:attr/colorPrimary"
+        android:background="@android:color/transparent"
         android:theme="@style/Theme.CollapsingToolbar.Settings">
 
         <com.google.android.material.appbar.CollapsingToolbarLayout

packages/SettingsLib/CollapsingToolbarBaseActivity/src/com/android/settingslib/collapsingtoolbar/widget/CollapsingCoordinatorLayout.java

@@ -20,6 +20,7 @@ import android.app.ActionBar;
 import android.app.Activity;
 import android.content.Context;
 import android.content.res.TypedArray;
+import android.os.Build;
 import android.text.TextUtils;
 import android.util.AttributeSet;
 import android.util.Log;
@@ -29,6 +30,7 @@ import android.widget.Toolbar;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+import androidx.annotation.RequiresApi;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.coordinatorlayout.widget.CoordinatorLayout;
 
@@ -41,6 +43,7 @@ import com.google.android.material.appbar.CollapsingToolbarLayout;
  * This widget is wrapping the collapsing toolbar and can be directly used by the
  * {@link AppCompatActivity}.
  */
+@RequiresApi(Build.VERSION_CODES.S)
 public class CollapsingCoordinatorLayout extends CoordinatorLayout {
     private static final String TAG = "CollapsingCoordinatorLayout";
     private static final float TOOLBAR_LINE_SPACING_MULTIPLIER = 1.1f;