fix(xcat-core): add the missing ppc64le netboot templates for EL8/EL9

copycds only defines a <osver>-<arch>-netboot-compute osimage when the netboot
compute pkglist/exlist/postinstall for that distro+arch exist under
share/xcat/netboot/<distro>/. For AlmaLinux the ppc64le set was present only for
alma10, so on an el8/el9 ppc64le management node copycds created just the
install-* osimages and no netboot one.

The stateless provisioning test then fails in a confusing way: the case's own
`chdef -t osimage -o <osver>-ppc64le-netboot-compute synclists=...` auto-creates
a bare object, so lsdef reports the image exists (imagetype=NIM and nothing
else), while genimage rejects it with

    Error: Cannot find image '<osver>-ppc64le-netboot-compute' from the osimage table.

and packimage plus the install that follows fail with it.

Two gaps are filled:
- share/xcat/netboot/rh/compute.rhels9.ppc64le.pkglist did not exist at all
  (rhels8 and rhels10 both ship one). Add it with the same content as the
  rhels9 x86_64 list, matching rhels10 where the two arches are identical.
- alma8/alma9 ppc64le compute exlist/pkglist/postinstall are added as symlinks
  into the rh/ equivalents, exactly as alma10 ppc64le and rocky10 ppc64le
  already do.

With these present, copycds produces a fully populated netboot-compute osimage
(provmethod=netboot, pkglist/exlist/postinstall/rootimgdir set) as it already
does on alma10 ppc64le.

Signed-off-by: Daniel Hilst <392820+dhilst@users.noreply.github.com>
(cherry picked from commit 8bb0606120)

xCAT-server/share/xcat/netboot/alma/compute.alma8.ppc64le.exlist

@@ -0,0 +1 @@
+../rh/compute.rhels8.ppc64le.exlist

xCAT-server/share/xcat/netboot/alma/compute.alma8.ppc64le.pkglist

@@ -0,0 +1 @@
+../rh/compute.rhels8.ppc64le.pkglist

xCAT-server/share/xcat/netboot/alma/compute.alma8.ppc64le.postinstall

@@ -0,0 +1 @@
+../rh/compute.rhels8.ppc64le.postinstall

xCAT-server/share/xcat/netboot/alma/compute.alma9.ppc64le.exlist

@@ -0,0 +1 @@
+../rh/compute.rhels9.ppc64le.exlist

xCAT-server/share/xcat/netboot/alma/compute.alma9.ppc64le.pkglist

@@ -0,0 +1 @@
+../rh/compute.rhels9.ppc64le.pkglist

xCAT-server/share/xcat/netboot/alma/compute.alma9.ppc64le.postinstall

@@ -0,0 +1 @@
+../rh/compute.rhels9.ppc64le.postinstall

xCAT-server/share/xcat/netboot/rh/compute.rhels9.ppc64le.pkglist

@@ -0,0 +1,30 @@
+@minimal-environment
+chrony
+kernel
+net-tools
+nfs-utils
+openssh-server
+rsync
+tar
+util-linux
+wget
+python3
+tar
+bzip2
+bc
+dracut
+dracut-network
+rsyslog
+hostname
+e2fsprogs
+ethtool
+parted
+openssl
+dhclient
+openssh-clients
+bash
+vim-minimal
+rpm
+iputils
+perl-interpreter
+