jjb: xci: Refactor bifrost jobs to use the XCI clean VM

jjb: xci: Refactor bifrost jobs to use the XCI clean VM

We no longer run opnfv/bifrost jobs so drop all the references from
the configuration file. Moreover, make use of the releng-xci XCI clean
VM virtual machine to run the tests on a clean environment. Finally, we
drop the support for uploading logs to the artifacts.opnfv.org. This
needs to be done for XCI as well so we will bring it back when we
develop a universal solution.

Change-Id: I9bad17508ab8ee6594aec444ab864b99331b616d
Signed-off-by: Markos Chandras <mchandras@suse.de>