Restart Bypassable VPNs when changing lockdown mode state

This change ensures that VPNs are restarted when the lockdown mode
changes. Lockdown VPNs can't be bypassable, and the stack doesn't
treat bypassable an non-bypassable VPNs the same way so the agent
has to be restarted when lockdown mode changes.

Bug: 246162564
Test: atest FrameworksNetTests:VpnTest
Change-Id: Ia0eec71310848ac20c98cf2b16f55ca5b7f8ff7f