Fixed uninformative variable name

 * Variable named "uname", used for the technicians' username
   replaced with variable named "technician_username".

Note: This change applies across a couple of projects. Make sure
      all relevant projects are updted. The variable is defined
      in the user role.

Issue: IWSoftware/ekahau-rtls-playbook#1
Ticket: #5507

Signed-off-by: Nathan Callister <ncallister@iwsoftware.com.au>