fix(utils): log mkfs.ext4 error output

Prior to this, if `mkfs.ext4` failed, all we saw was "failed to
format /dev/sda. err: exit status 1".  With this change, we'll
see the command output, which is a bit more useful, for exmaple:
"failed to format /dev/sda. exit status 1: mke2fs 1.46.4
(18-Aug-2021) /dev/sda is apparently in use by the system;
will not make a filesystem here!"

Signed-off-by: Tim Serong <tserong@suse.com>
(cherry picked from commit 81e8774)

pkg/utils/utils.go

@@ -76,8 +76,9 @@ func MakeExt4DiskFormatting(devPath, uuid string) error {
 		args = append(args, "-U", uuid)
 	}
 	cmd := exec.Command("mkfs.ext4", args...)
-	if _, err := cmd.CombinedOutput(); err != nil {
-		return fmt.Errorf("failed to format %s. err: %v", devPath, err)
+	if output, err := cmd.CombinedOutput(); err != nil {
+		return fmt.Errorf("failed to format %s. %v: %s", devPath, err,
+			strings.ReplaceAll(strings.TrimSpace(string(output)), "\n", " "))
 	}
 	return nil
 }