Take advantage of ssh-free `drunc`

[jcfreeman2]

Once DUNE-DAQ/drunc#476 is approved, allowing for ssh-free use of drunc, we should take advantage of this since pytest runs the integration tests just on a local host. This could be as simple as changing the ssh-standalone argument passed to drunc-unified-shell over to popen-standalone.

[jcfreeman2]

...in fact, Pierre already thought of this: #110