Fix launch flags for channel panel

To fix the interaction with the sound picker

Test: launch sound picker from panel, ensure result saved
Test: launch sound picker from panel, cancel
Test: launch more than one panel, make sure all can be edited
Test: change sound from full channel settings page

Fixes: 195739942
Change-Id: I9df86507f8f0cfdd1b0935ca9fe056d24b6d6eac

AndroidManifest.xml

@@ -2862,9 +2862,7 @@
         <activity android:name=".notification.app.ChannelPanelActivity"
                   android:label="@string/notification_channel_title"
                   android:theme="@style/Theme.Panel"
-                  android:launchMode="singleInstance"
                   android:excludeFromRecents="true"
-                  android:noHistory="true"
                   android:configChanges="orientation|keyboardHidden|screenSize"
                   android:exported="true">
             <intent-filter android:priority="1">