systemd/ceph-disk@.service assumes /bin/flock
It may be elsewhere (/usr/bin/flock etc.)
build/ops: systemd ceph-disk unit must not assume /bin/flock
The flock command may be installed elsewhere, depending on the
system. Let the PATH search figure that out.
Signed-off-by: Loic Dachary <email@example.com>
(cherry picked from commit c8f7d44c935bd097db7d131b785bdab78a7a650c)