CI: Improvements on the COTS-UE bench script

  * added banner to pipeline script
  * added parameters to Jenkins pipeline / python
    * xmlfile and test stage
  * eNB configuration files are located under ci-scripts/conf_files
    * no more correction of MNC
    * still correction of EPC / eNB IP addresses at runtime
    * Initialize_eNB_args is back using the proper "-O " syntax
  * Terminate stage is parallel as in FJU's original pipeline
  * Log collection stage is back fully parallel
  * Console as artifact an option
  * Check if terminate calls ended well, to be repeated at the end
  * Adding back iperf:
    * selection of iperf vs iperf3
    * adding some iperf testcases to test suite
  * Better enb launch

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>