Maintain VPN type form the VpnProfile

the connectedLegacyVpn may already exist within the VpnProfiles. Because
the stub profile generated from the LegacyVpnInfo does not contain type
information, overriding whether the VPN is insecure using this
information will provide an incomplete picture.

Test: atest -c SettingsUnitTests
Bug: 184922172
Change-Id: Icf2e08826c444863eaebdaa47bfd217795d2bad6