Show correct visual effects for modes with interruption filter NONE or ALARMS

In Settings, we were displaying a blocking-all-visual-effects policy for rules with nonstandard interruption filters. In reality, only the set of allowed sounds is fixed, while the visual effects come from the default policy (or, if other rules are active, from them). So merging with the default policy is way more accurate.

Fixes: 363999223
Fixes: 361591317
Test: atest ZenModeTest ZenModesBackendTest
Flag: android.app.modes_ui
Change-Id: I043862f327534851f96cd4daf596500e7f0ec012