Add interface-names to centos8 images

Back in Bug #1841441, we disabled the net.ifnames because of the
RHEL7->RHEL8 changes to interface names. Now that we have centos8, we
need to ensure this action is also run on those images.

Depends-On: https://review.opendev.org/#/c/712947/
Change-Id: Ice40fec0eacefd9778614996fb3417b78cdd17d3
Related-Bug: #1866202
Related-Bug: #1841441
(cherry picked from commit 2589b8f22a)

image-yaml/overcloud-hardened-images-centos8.yaml

@@ -7,3 +7,4 @@ disk_images:
       DIB_RELEASE: '8'
     elements:
       - selinux-permissive
+      - interface-names

image-yaml/overcloud-images-centos8.yaml

@@ -6,6 +6,7 @@ disk_images:
     release: 8
     elements:
       - selinux-permissive
+      - interface-names
     environment:
       FS_TYPE: xfs
     options:
@@ -17,3 +18,4 @@ disk_images:
     release: 8
     elements:
       - selinux-permissive
+      - interface-names

image-yaml/overcloud-images-ceph-centos8.yaml

@@ -6,3 +6,4 @@ disk_images:
     release: 8
     elements:
       - selinux-permissive
+      - interface-names