Fixes #3934 - Backport Technique 'Package management for RHEL / CentOS / SuSE / RPM systems' v4.1 to branch 2.4
Refs #3934 - Remove displayPriority which is Rudder 2.6 feature
Merge pull request #187 from nperron/ust_3919/dev/3934_backport_rpmInstall_v4.1

Fixes #3934 - Backport Technique 'Package management for RHEL / CentOS / SuSE / RPM systems' v4.1 to branch 2.4