CI: write whole etc/issue for domU initrd

Upcoming changes won't unpack original rootfs anymore, so sed on
existing file cannot be used. Override the whole file instead.

No functional change intended.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
(cherry picked from commit f401eae6ec)

automation/scripts/qubes-x86-64.sh

@@ -182,7 +182,10 @@ ${domU_check}
 " > etc/local.d/xen.start
     chmod +x etc/local.d/xen.start
     echo "rc_verbose=yes" >> etc/rc.conf
-    sed -i -e 's/^Welcome/domU \0/' etc/issue
+    echo "domU Welcome to Alpine Linux
+Kernel \r on an \m (\l)
+
+" > etc/issue
     find . | fakeroot -i ../fakeroot-save cpio -H newc -o | gzip > ../binaries/domU-rootfs.cpio.gz
     cd ..
     rm -rf rootfs

automation/scripts/xilinx-smoke-dom0-x86_64.sh

@@ -65,7 +65,10 @@ ${DOMU_CMD}
 " > etc/local.d/xen.start
 chmod +x etc/local.d/xen.start
 echo "rc_verbose=yes" >> etc/rc.conf
-sed -i -e 's/^Welcome/domU \0/' etc/issue
+echo "domU Welcome to Alpine Linux
+Kernel \r on an \m (\l)
+
+" > etc/issue
 find . | cpio -H newc -o | gzip > ../binaries/domU-rootfs.cpio.gz
 cd ..
 rm -rf rootfs