watchman: chown in watchman@.socket unit allows symlink attack

A UNIX Symbolic Link (Symlink) Following vulnerability in the systemd service file for watchman of openSUSE Backports SLE-15-SP3, Factory allows local attackers to escalate to root. This issue affects: openSUSE Backports SLE-15-SP3 watchman versions prior to 4.9.0. openSUSE Factory watchman versions prior to 4.9.0-9.1.