scap: ensure=>absent /usr/local/bin/sync-common-file

Sync-dir and sync-file have been ported to python with I5ab7b2f and the
sync-common-file helper script has been removed from
mediawiki/tools/scap.git. Clean up the dangling symlink on the cluster.

Change-Id: I448f574e9ccf7de1a7f4a254175f7ac36cd44ff6