Add in sandbox UIDs when configuring VPN.

SDK sandboxes that belong to an application should follow the same VPN
configuration that their corresponding app does.

Bug: 225317905
Test: atest VpnTest
Change-Id: I634f47a013fa2e42908d963fcd0634778298fee5
Merged-In: I634f47a013fa2e42908d963fcd0634778298fee5