[Wipe node playbook] Failure to remove apt packages when a lock is present.

[vreniers]

While running the wipe node playbook, in currently the final step, it removes all scylla-related packages.
In one case, I observed an error in which seemingly another process was holding a dpkg lock, failing the removal of such packages.

TASK [Remove Scylla packages]
...
E: Could not get lock /var/lib/dpkg/lock-frontend. It is held by process XXX (unattended-upgr)

I omitted the process ID, and did not see such a process running when inspecting the machine.

• We could set retries on this task, as well as a certain delay, to try a few times.