Handle hostname-prefixed md device names and clear stale superblocks

Newer mdadm versions may load arrays under names like
`/dev/md/<hostname>:raid` after reboot instead of `/dev/md/raid`. Detect both
naming schemes when waiting for the array device and use the resolved
path consistently when determining the underlying md device name.

Also clear existing md superblocks before wiping signatures to avoid
stale RAID metadata interfering with array creation or assembly.

misc/swraid

@@ -7,6 +7,7 @@ NUMDEVS=$(for dev in $DEVICES; do
    echo wipefs -a -f $dev
 done|wc -l)
 for dev in $DEVICES; do
+   mdadm --zero-superblock $dev
    wipefs -a -f $dev
 done
 # must use older metadata format to leave disks looking normal for uefi
@@ -15,9 +16,15 @@ mdadm -C /dev/md/raid $DEVICES -n $NUMDEVS -e 1.0 -l $RAIDLEVEL -b internal
 mdadm -S -s
 mdadm --assemble --scan
 )
-while [ ! -e /dev/md/raid ]; do
+while :; do
+    # newer mdraid verions might have <hostname>:<raidname>
+    TARGET_RAID=$(ls /dev/md/raid /dev/md/*:raid 2>/dev/null | head -n 1)
+
+    [ -n "$TARGET_RAID" ] && break
+
     echo 'Waiting on array to be linked...'
     sleep 0.5
 done
-readlink /dev/md/raid|sed -e 's/.*\///' > /tmp/installdisk
 
+# Extract the underlying block device name (e.g., md127) using the captured path
+readlink "$TARGET_RAID" | sed -e 's/.*\///' > /tmp/installdisk