[DO NOT MERGE] Add android:relinquishTaskIdentity for multi-pane

Allow CustomizationPickerActivity to relinquish its task identity for
multi-pane case.

Bug: 202465727
Test: Manual
Change-Id: I1916d61d646eeb01329a6f592f14b7a3ca7cd5f7
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index ccadc12..c6e79a9 100755
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -52,6 +52,7 @@
             tools:node="replace"
             android:name="com.android.wallpaper.picker.CustomizationPickerActivity"
             android:label="@string/app_name"
+            android:relinquishTaskIdentity="true"
             android:resizeableActivity="false"
             android:theme="@style/CustomizationTheme.NoActionBar"
             android:exported="false"/>