With the addition of connect_bssid/roam very few tests actually
require hwsim. Since hwsim can lead to problems with scan results
its best to have it off by default and have each test that needs
it explicitly turn it on.
Tests which previously turned it off have had that option removed.
Tests that do require hwsim still are vulnerable to scan result
problems, so for these tests beacon_int was added to the hostapd
config which seems to help with reliability somewhat.
The existing AP tests needed to be modified to start IWD from
python since the DHCP test uses a different main.conf.
Also removed some stale hw.conf options that are no longer used.
