[AT-1790] - Update set_cluster to allow for different namespace formats.

The set_cluster method is a bit problematic to work with.

The namespace passed in is not the whole namespace, the method appends the telescope name to it (e.g. -mid or -low). This makes it impossible to use if your namespace does not end with these suffixes. This change removes that requirement: users will now have to enter the actual namespace when using set_cluster. This also allows the ITF notebook to use this method so the set_cluster_mid workaround can be removed.

Ran the jupyter_notebook_for_mid_imaging_scenario_multi_scan_sb.ipynb notebook with a Skampi namespace and setting the cluster in this way worked. There was a schema-related failure in the Assign Resources section of the Notebook, I assume this is unrelated.