Disable always-on VPN in factoryReset

When network setting reset is started while always-on VPN is enabled,
application crash occurs with IllegalStateException in prepareVpn().

Therefore, it's necessary to also disable always-on VPN in factoryReset
before prepareVpn() when turning off VPN.

Bug: 29030858
Change-Id: I08c5406717dd7937d197c2e934a56d037477aafc
1 file changed