Exempt exact alarms from the stock limit.

Allow apps to set and use exact alarms even if the TARE system has run
out of consumable stock. Since apps need to hold the
SCHEDULE_EXACT_ALARM or USE_EXACT_ALARM permissions to use exact alarms,
we can be a little more lenient with the check. Enforcing the stock
limit check could result in some unexpected user journeys. We continue
to apply the app balance check so apps can't runaway with exact alarms.

Bug: 258032540
Test: atest frameworks/base/services/tests/mockingservicestests/src/com/android/server/tare
Test: atest frameworks/base/services/tests/servicestests/src/com/android/server/tare
Change-Id: I307fe35370e0450d2248e4bbdbcf0c00839d3214