Potential issue with working directory in the `rules_loop.sh`

[ThomasShih]

This doesn't need to be the final outcome, but when I was going through the guide, I couldn't figure out for the life of me why areas wasn't working. Turns out that the way this script is set up means that I had to execute the script from a working directory of / in order for the pwd in the deleted changes to work.

I think we can also pretty it up a bit (I'm not sure why we exactly need to sanitize the $EXEC_DIR as a relative of our invoking directory, I think there is a bug here if we executed without absolute.

I think we can simplify the two down to just forgetting about relative execution, since the guides from osm wiki tells us to execute via the absolute path (nohup $EXEC_DIR/bin/rules_loop.sh $DB_DIR &, where the two env vars are stored as abolutes)