Move generate_tests earlier in entry scripts

Move generate_tests earlier in entry scripts

The idea is to run test generation and archivation
before testbed reservation, as during generation and archivation
the testbed can be used by another job.
The two steps are moved just before (physical or docker) reservation,
as they currently take considerable time,
so simpler steps are kept before to save time if they fail.
Coincidentally, it is also just after activate_virtualenv,
Python is needed for test generation.

Change-Id: I8b41b91dba8118e89301e3fcf89d5cd14ac054a2
Signed-off-by: Vratko Polak <vrpolak@cisco.com>