remove accessibility label from ExpandableNotificationRow when snoozed

The snoozed notifications had an extra accessibility label when
accessing it from "Voice Access" and the "Switch Access" found it twice
as well. The issue can be solved by setting the parent view as it is not important for accessibility.

Test: ExpandableNotificationRowTest

Bug: 182127168
Bug: 182236319
Change-Id: I32ce84fafa0372516aaf75b714a21c076a670dd5