Move static settings from run-tempest into conf

The run-tempest script sets several configuration values to
static settings. With pass-through enabled such settings
should be moved instead into the tempest.conf template file.

Change-Id: I6c4aa79a0676e2cb651f29249b2ac83ec6d3df0e
Add a tempestrunrc for configuring run-tempest

Add a tempestrunrc file which is sourced by run-tempest
to get input settings such as image-name and concurrency.

Variables in tempestrunrc can be via the ExtraConfig of
the image where the element is deployed.

Change-Id: I24b04b22e911732ffb9884a15cc45afabc02100a
Merge "Move static settings from run-tempest into conf"
Merge "Add a tempestrunrc for configuring run-tempest"