Also await IpClient's shutdown

It may be best to await shutdown of IpClient, especially in cases
where cleanup code would otherwise race with IP address assignment
and other bringup code.

Test: as follows
    - built
    - flashed
    - booted
    - frameworks/opt/net/wifi/tests/wifitests/runtests.sh passes
Test: Unit test
Test: Ran WifiManager ACTS tests locally.
Bug: 79400794
Change-Id: I1a02d70660ec54fda9a36399b285cda054cde8d3
2 files changed