Fix RPM installation at p5

Description

This MR aims at fixing a few issues in the RPM discovered when updating the machines at p5 to CentOS 7.9. Namely:

• Fix the systemd services installation on CentOS 7.9
• Set setuid bit for DPDK applications in RPM
• Include empty directories in cmsgemos RPM (this targets at first the /etc/cmsgemos directory)

Related Issue

How Has This Been Tested?

The CI produces nice and clean RPMs.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.