Verify lock down related flows

This commit verifies the lock down related flows:
- When a user present
- When lock down is reset
- Create LockdownVpnTracker
- isVpnLockdownEnabled(int)
- getVpnLockdownAllowlist(int)

Bug: 230548427
Test: atest VpnManagerServiceTest
Change-Id: Ic42d884b64d2c7ec0caf9dff95d94fc5e52456b2
1 file changed