Suppress HUNs for notifications with old whens

Right now, if a user turns their device (or work profile) on after it's
been off for a while, they can get flooded with visual interruptions
(like heads-up notifications) from 'stale' notifications -- recently
posted, but pertaining to something that happened over a day ago.

This change will, when the included feature flag is enabled, suppress
visual interruption for notifications with a 'when' field set more than
24 hours in the past.

Bug: 240552967
Bug: 253055301
Test: atest StatusBarNotificationPresenterTest
Change-Id: I6e8b29cd9865370fb5ad34d4b74e0f8a40e63229