Prepare parallel execution of e2e tests to run against multiple vcenter versions

[lmalvins]

Details:
As part of a well sanity check, it is needed an execution of our e2e tests against multiple vcenter versions.

Acceptance Criteria:

• Use independent source folders (log folder, ova folder, and checked out code folder) for each job.
• Pass vcenter and exsi version as parameters to vicui-common.robot, and setup-testbed.robot instead the hardcoded ones.
• Delete the generated folder except the generated logs.