Update perf scale pipelines to use Loki stable-6.0 channel for OCP >= 4.17
openshift-qe/ocp-qe-perfscale-ci#645: NETOBSERV-1878 use loki 6.0 channel for OCP >= 4.17
Merge request - NETOBSERV-1878 use unreleased Loki 6.0 until its GA