Use a switch statement instead of static list of layouts

The static list is not very scalable when we need to add things behind
flags, so let's just use a switch statement.

Bug: 378660052
Test: presubmint
Flag: android.app.notifications_redesign_templates
Change-Id: I560c6f7c09cd82860dd17a9af2e6cfc88455cd05
1 file changed