Update VPNaaS package for RHEL

OpenSwan Package for IPSec has been replaced with libreswan in EL9.
We missed to reflect that while adding EL9 support.

Closes-Bug: #2039098
Change-Id: I04742324ff472b3c40ee4c7d333305c67046aba2
(cherry picked from commit ef4d327)

vars/redhat.yml

@@ -86,7 +86,7 @@ neutron_lxb_distro_packages:
   - bridge-utils
 
 neutron_vpnaas_distro_packages:
-  - openswan
+  - libreswan
 
 _neutron_driver_vpnaas: neutron_vpnaas.services.vpn.device_drivers.libreswan_ipsec.LibreSwanDriver
 _neutron_vpnaas_service_provider: VPN:openswan:neutron_vpnaas.services.vpn.service_drivers.ipsec.IPsecVPNDriver:default