community/texlive: finally fix trigger script
- the post-upgrade hook is not needed, as updating either texlive or
texmf-dist will run texlive.trigger anyway
- in fact, the post-upgrade will run right after the upgrade, and not once also texmf-dist has been upgraded (if both are upgraded at the same time).
- the previous script didn't fix all issues. The new trigger script is
hopefully bullet proof
- some output has been added so that uses see some progress during the trigger. It takes now a bit of time to complete