Add rocky support to the epel element

OpenDev relies on the epel role to configure the epel repository for our
image builds. Specifically we need epel to pull in haveged. Update the
epel role to recognize rocky and configure it properly.

Change-Id: I968d4702ef39590e972b782a09e18a5db40703ad

diskimage_builder/elements/epel/pkg-map

@@ -11,6 +11,10 @@
     "rhel7": {
        "wget": "wget",
        "yum-utils": "yum-utils"
+    },
+    "rocky": {
+       "wget": "wget",
+       "yum-utils": "yum-utils"
     }
  },
  "default": {

diskimage_builder/elements/epel/pre-install.d/05-rpm-epel-release

@@ -6,7 +6,7 @@ fi
 set -eu
 set -o pipefail
 
-if [[ ${DISTRO_NAME} =~ "centos" && "${DIB_RELEASE%-stream}" -lt '9' ]]; then
+if [[ (${DISTRO_NAME} =~ "centos" || ${DISTRO_NAME} =~ "rocky") && "${DIB_RELEASE%-stream}" -lt '9' ]]; then
     # Centos has "epel-release" in extras, which is default enabled.
     ${YUM} install -y epel-release
 else

diskimage_builder/elements/rocky-container/test-elements/build-succeeds/element-deps

@@ -1,2 +1 @@
-openstack-ci-mirrors
 vm