tests: Move 'reverse' calls inside 'setUp'

Django creates test databases after it loads tests. However, any
operations that exist at class level will be executed before this
database is created. Fix the instances of this issue (mostly 'reverse'
calls or similar) by moving the calls into the relevant 'setUp'
functions for each test.

Acked-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Stephen Finucane <stephen.finucane@intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>