pytest/sddl: replace/export tests based on environment vars
We had a stupid system involving test functions with side-effects,
that needed to be enabled by editing the file. Now you get the same
effects by setting environment variables, the names of which you can
only learn by reading the file closely.
This works better because some stuff needs to happen at class-time
rather than instance-time.
Also the environment variables specify the import and export locations.
Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>