Added tempest job to manila project

With addition was updated existing tempest job.
Purpose of having two tempest jobs:
Test single backend manila installation and multi backend
manila installation.

Moved most of exported env vars to separate bash script
to have possibility debug configuration of job and minimize
commitment to config project.

Also removed usage of these jobs in gate pipeline.

Partially implements: blueprint multibackend-installation-tempest-job

Change-Id: I201ab1e5bf2ac8a4bcd7985e010751704f8e26ae
Merge "Added tempest job to manila project"