(#22324) Generalize distmoduledir setting for windows module install

The pe test changes were using a Beaker host setting
agent['distmoduledir'] which was not set for hosts of type Windows.
Furthermore, the actual value is dependent on confdir which varies
by verison according to COMMON_APPDATA, and so is not practicle to set
in the base Beaker Windows host settings.  So I'm setting it based on
the returned confdir setting from the puppet agent on the host.