Description
"show arp " show the entries after age out, The reason is it follows linux standard display.
root@switch2:/home/admin# show arp
Address HWtype HWaddress Flags Mask Iface
12.12.12.5 ether 00:10:94:00:00:02 C Ethernet1
11.11.11.5 ether 00:10:94:00:00:01 C Vlan2
10.6.48.254 ether 78:48:59:fc:14:01 C eth0

src/sonic-utilities/show/main.py.
def arp(ipaddress, verbose):
"""Show IP ARP table"""
-cmd = "/usr/sbin/arp -n"
+cmd = "ip -s neighbor list"

root@switch2:/# show arp
10.0.0.3 dev Ethernet4 used 81662/85265/81659 probes 6 FAILED
10.0.0.21 dev Ethernet40 used 108/85260/105 probes 6 FAILED
10.41.8.253 dev eth0 lladdr 4c:77:6d:87:0c:0c used 67291/70891/9813 probes 0 STALE
10.41.8.219 dev eth0 lladdr 00:50:54:80:7b:ba used 69308/72908/11707 probes 0 STALE
10.41.8.209 dev eth0 lladdr 00:b0:64:fd:4b:75 used 72306/75906/606 probes 0 STALE
10.41.8.254 dev eth0 lladdr b4:b5:2f:a8:36:c0 ref 1 used 1368/1363/765 probes 1 REACHABLE

Steps to reproduce the issue:

1. show arp

Describe the results you received:

Describe the results you expected:

Additional information you deem important (e.g. issue happens only occasionally):

**Output of `show version`:**

```
(paste your output here)
```

**Attach debug file `sudo generate_dump`:**

```
(paste your output here)
```