They don’t use those terms anymore as I discovered when talking to a great friend who is very decorated by the establishment for being a “Head Teacher”.
I honestly can see middle schoolers snickering at the fact that their school's authority figure is seriously and officially referred to as "head" teacher.
Master of Ceremony, Master Switch, Gramdmaster
Master Boot Record
Master of Social Science ... ohhhh
Dammit I got called to the head default room again...
None of which have any association with master/slave, unlike git where the convention of calling the default branch "master" comes from BitKeeper, with its master/slave repositories.