In the U.K. “Flightstore” (Other suppliers are probably available ) supply an XLR to 2 plug adaptor with pin 5 already disconnected. I’ve been using one of these on B737 for the last 15 years with a Telex 850 ANR headset which runs off the aircraft mic bias current.
Headset works fine, and four airlines I’ve worked for have been happy with it, all with the same requirement as yours.