Consolidate centos/fedora/redhat required_defaults

There's very little difference in the package lists. I'm just
guessing there, but I believe g++ and xml2/xslt devel packages are
for working with libvirt, and the python3-selinux either comes
pre-installed or is installed at some earlier point by other
playbooks.

Change-Id: I5865c65cae695491524a8828c8abb48393a197a0

playbooks/roles/bifrost-create-vm-nodes/defaults/required_defaults_CentOS.yml

@@ -1,15 +0,0 @@
----
-sgabios_dir: /usr/share/sgabios/
-libvirt_service_name: libvirtd
-required_packages:
- - qemu-img
- - kernel-tools
- - qemu-kvm
- - sgabios-bin
- - libvirt
- - libvirt-client
- - libvirt-daemon
- - libvirt-daemon-kvm
- - python3-libvirt
- - edk2-ovmf
-test_vm_emulator: "/usr/libexec/qemu-kvm"

playbooks/roles/bifrost-create-vm-nodes/defaults/required_defaults_Fedora.yml

@@ -1,14 +0,0 @@
----
-sgabios_dir: /usr/share/sgabios/
-libvirt_service_name: libvirtd
-required_packages:
- - qemu-img
- - qemu-kvm
- - sgabios-bin
- - libvirt
- - libvirt-client
- - libvirt-daemon
- - libvirt-daemon-kvm
- - python3-libvirt
- - python3-libselinux
- - edk2-ovmf

playbooks/roles/bifrost-create-vm-nodes/defaults/required_defaults_RedHat.yml

@@ -12,6 +12,8 @@ required_packages:
  - libvirt-daemon
  - libvirt-daemon-kvm
  - python3-libvirt
+ - python3-libselinux
  - libxslt-devel
  - libxml2-devel
  - edk2-ovmf
+test_vm_emulator: "/usr/libexec/qemu-kvm"