Replace some more "command -v" calls with the Helper method

Remove some more output mid-unittests on windows.

Second part from #12303 

@MorrisJobke @icewind1991 @LukasReschke 
checkDependencies() is supposed to return true, or the reason why it is not working, in terms of missing deps.
In this case we now either return true, if smbclient is there, or we return an array with the missing dep, just like before.