pytest: samba-tool: coalesce run*cmd functions

pytest: samba-tool: coalesce run*cmd functions

We have had three different functions for resolving samba-tool commands,
depending on whether they are nested 1, 2, or n deep (where n could also
be 1 or 2). This API evolved around a separation of sub-command names and
options, so that the Command that was eventually found could be given the
right outf and errf.

Now we can just use the same outf and errf for all levels, and we can not
care about this distinction.

All these functions are now synonyms, and we keep them all for now for
backward-compatibility.

Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>