xargs option conflict now a warning in el9

The warnings thrown by el9's version of xargs are unexpected output and
cause this test to fail. When using the -I option (replace) the -n 1
arguments are always assumed. In el7/8 no warnings were printed.

We can just remove `-n 1` since the argument is never needed.

Signed-off-by: Auke Kok <auke.kok@versity.com>

tests/tests/quota.sh

@@ -22,7 +22,7 @@ reset_all()
 	getfattr --absolute-names -d -m - "$T_D0" | \
 		grep "^scoutfs.totl." | \
 		cut -d '=' -f 1 | \
-		xargs -n 1 -I'{}'  setfattr -x '{}' "$T_D0"
+		xargs -I'{}'  setfattr -x '{}' "$T_D0"
 }
 
 echo "== prepare dir with write perm for test ids"