Create P2P VTS test networks using

addGroup() instead of addNetwork().

Verified by running the affected VTS tests
on an AOSP and an internal main build.
Previously, the test was passing on AOSP,
but failing on the internal builds.

Bug: 387556129
Bug: 387925327
Test: atest VtsHalWifiSupplicantP2pIfaceTargetTest
Test: atest VtsHalWifiSupplicantP2pNetworkTargetTest
Change-Id: Id135270f3c353c2cdcfb47905fb6748b0b22b70f