Micro AIs: make recruit_rushers work with new external CA method

The previous code did not allow to get the ai table to the execution
function.
Recruiting MAI test scenario: add Rush Recruitment MAI for Side 2
Experimental AI: make Healer Placement CA work with new external CAs

Healer Placement is a Micro AI whose syntax was changed in the switch
to using external AIs.  This change adapts how this CA is called in the
Experimental AI (gerneric rush AI) to these changes.