Fix volume/nfs image for CentOS Stream 9

The volume/nfs:1.5 image was updated from CentOS 8 to CentOS Stream 9
in commit 9b47a096f4, but this broke NFS server startup because
NFSv2 is no longer supported in RHEL 9 / CentOS Stream 9.

The `-N 2` flag (disable NFSv2) passed to rpc.mountd and rpc.nfsd
causes them to fail with "2: Unsupported version" since there's no
NFSv2 to disable. This prevented rpc.nfsd from starting, causing
NFS mount timeouts in e2e tests.

Fix by removing the `-N 2` flags. NFSv2 is already unavailable in
CentOS Stream 9, so explicitly disabling it is unnecessary.

Red Hat documentation states: "NFS version 2 (NFSv2) is no longer
supported by Red Hat."

Reference: https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/9/html/managing_file_systems/mounting-nfs-shares_managing-file-systems

Signed-off-by: Davanum Srinivas <davanum@gmail.com>

test/images/volume/nfs/VERSION

@@ -1 +1 @@
-1.5
+1.6.0

test/images/volume/nfs/run_nfs.sh

@@ -51,11 +51,11 @@ function start()
     mount -t nfsd nfsd /proc/fs/nfsd
 
     # -V 3: enable NFSv3
-    /usr/sbin/rpc.mountd -N 2 -V 3
+    /usr/sbin/rpc.mountd -V 3
 
     /usr/sbin/exportfs -r
     # -G 10 to reduce grace time to 10 seconds (the lowest allowed)
-    /usr/sbin/rpc.nfsd -G 10 -N 2 -V 3
+    /usr/sbin/rpc.nfsd -G 10 -V 3
     /usr/sbin/rpc.statd --no-notify
     echo "NFS started"
 }