Set mar IDs as env variables in tor-browser-build
We used to set ACCEPTED_MAR_CHANNEL_IDS
and MAR_CHANNEL_ID
in browser/confvars.sh
(see tor-browser@6c32a8f6).
However, after Bug 1943612, that file can strictly contains only key and values.
It seems that these values must be set with environment variables, and upstream does so in CI. (These are their values).
So, we probably have to do the same, and set these variables here in tor-browser-build, it should be pretty easy.