Audio focus: no "strong duck" for navigation use case

Only USAGE_ASSISTANT qualifies for strong duck.

Bug: 283690263
Test: play driving directions while playing media
Change-Id: If6bbd9b50d0ce14fc194a4d214fd208702688926

services/core/java/com/android/server/audio/PlaybackActivityMonitor.java

@@ -812,8 +812,7 @@ public final class PlaybackActivityMonitor
             return false;
         }
         final int reqUsage = requester.getAudioAttributes().getUsage();
-        if ((reqUsage == AudioAttributes.USAGE_ASSISTANT)
-                || (reqUsage == AudioAttributes.USAGE_ASSISTANCE_NAVIGATION_GUIDANCE)) {
+        if (reqUsage == AudioAttributes.USAGE_ASSISTANT) {
             return true;
         }
         return false;