[Keyguard] Filter provisioning class subscriptions

More recently, there are subsciptions that can come down from
`getCompleteActiveSubscriptionInfoList` which have a `profileClass` of
`PROFILE_CLASS_PROVISIONING`.

Per b/314896607, we want to filter these out. This logic matches what
has already been released in `MobileIconsInteractor`.

Also, updated `KeyguardUpdateMonitorTest#testActiveSubscriptionBecomesInactive`
since SubscriptionManager will never return null from that API.

Inside of KeyguardUpdateMonitor, reworked some of the logic that looked
redunant for fetching subscriptions, and added the filter directly to `getSubscriptionInfo`

Test: KeyguardUpdateMonitorTest
Fixes: 314896607
Flag: NONE
Change-Id: Ifede0aa90d14ffbd54664c8cec84d62dcf767f25