Fixed broken URL in isle git cleanup script.sh

[g7morris]

The maintainer of the involved jar file moved the binary. I've updated the link from:

• http://search.maven.org/classic/remotecontent?filepath=com/madgag/bfg/1.13.0/bfg-1.13.0.jar (results in a broken tiny binary and a silent error when running the script.)

to

• https://repo1.maven.org/maven2/com/madgag/bfg/1.13.0/bfg-1.13.0.jar (results in correct 13 MB binary which completes entire script)