Change tgt pkg-map to target-restore CentOS/RHEL-8

In ironic-agent tgt pkg-map, scsi-target-utils was used for
redhat family which is not used in CentOS/RHEL-8.

As per https://opendev.org/openstack/ironic-python-agent-builder/src/branch/master/dib/ironic-python-agent-ramdisk/pkg-map#L5
targetcli got removed and switch to target-restore. It syncs
the same element for RHEL-8 and adds the same for CentOS-8.

Closes-Bug: #1864427

Change-Id: I95a0c09a6739af23cd1e8c88dded198bd69cc53e
Signed-off-by: Chandan Kumar (raukadah) <chkumar@redhat.com>

diskimage_builder/elements/ironic-agent/pkg-map

@@ -2,7 +2,16 @@
   "release": {
     "rhel": {
       "8": {
-        "tgt": "targetcli",
+        "tgt": "target-restore",
+        "curl": "curl",
+        "ironic-python-agent": "openstack-ironic-python-agent",
+        "qemu-utils": "qemu-img",
+        "python-dev": "python3-devel"
+      }
+    },
+    "centos": {
+      "8": {
+        "tgt": "target-restore",
         "curl": "curl",
         "ironic-python-agent": "openstack-ironic-python-agent",
         "qemu-utils": "qemu-img",