change default folder for greenlight

[fireba11]

The default folder for greenlight sadly is /root/greenlight. That should be changed to /opt/greenlight or the like, see also https://github.com/bigbluebutton/greenlight/issues/2738 so we can reduce rights needed there.

[debuglevel]

It actually is ~/greenlight which is even worse, I think. Depending on the su/sudo method (sudo -i vs sudo -s) you're using it might be /root/greenlight or /home/user/greenlight. If multiple users are administrating a Greenlight host, and re-execute bbb-install.-sh -g in a sudo -s shell it will even get installed in different user homes and mess up the database, as directory bindings are used instead of docker volumes.

A workaround might be to pipe the script through sed to replace ~ with /opt :-/

wget -qO- https://ubuntu.bigbluebutton.org/bbb-install.sh | sed 's|~/greenlight|/opt/greenlight|g' | bash -s -- [...]