Remove VCN Carrier Privilege grace period

This change removes the grace period after the VCN is notified that a
provisioning app is no longer carrier privileged. This is due to the
switch to use CarrierPrivilegesTracker, which inherently has the
identical grace period.

This both simplifies the code, as well as removes some edge cases. As
such, tests for the delay before VCN tears down are no longer necessary.

Bug: 183554244
Test: atest FrameworksVcnTests
Change-Id: Ia50223108e45eeaedc860adf5e29a6ea459d956f