Remove sphinx.ext.jsmath #13747
Description
Having multiple javascript-based math renderers burdens the user with understanding the differences and deciding which one to use.
AFAICS sphinx.ext.mathjax is the way to go and there should be no reason to use sphinx.ext.jsmath.
Usage of sphinx.ext.jsmath is quite low: Searching for uncommented appearance in conf.py on github yields 82 matches, most of which have not been touched fo at least 5 years.
https://github.com/search?q=%2F%5E%5B%5E%23%5D*sphinx.ext.jsmath%2F+path%3Aconf.py&type=code
Therefore, I'd say that a deprecation can be skipped and we can immediately remove the extension. There appear to be no active users that would pick up the deprecation.