[bug] `show ip route bgp json` has redudant leading colon which is invalid json data

[w1nda]

Description

when using command show ip route bgp json I will get an invalid json data.
However, it I execute the command in vtysh, I can get the valid json data.
So, I think it's the show command has bug.

admin@xxxxx:~$ docker exec bgp vtysh -c 'show ip route bgp json' | head
{
  "0.0.0.0/0":[
    {
      "prefix":"0.0.0.0/0",
      "prefixLen":0,
      "protocol":"bgp",
      "vrfId":0,
      "vrfName":"default",
      "selected":true,
      "destSelected":true,
admin@xxxxx:~$ show ip route bgp json | head
:
{
  "0.0.0.0/0":[
    {
      "prefix":"0.0.0.0/0",
      "prefixLen":0,
      "protocol":"bgp",
      "vrfId":0,
      "vrfName":"default",
      "selected":true,
admin@xxxxx:~$ 

Steps to reproduce the issue

Use command show ip route bgp json or show ipv6 route bgp json

Describe the results you received

:
{
  "0.0.0.0/0":[
    {
      "prefix":"0.0.0.0/0",
      "prefixLen":0,
      "protocol":"bgp",
      "vrfId":0,
      "vrfName":"default",
      "selected":true,

Describe the results you expected

{
  "0.0.0.0/0":[
    {
      "prefix":"0.0.0.0/0",
      "prefixLen":0,
      "protocol":"bgp",
      "vrfId":0,
      "vrfName":"default",
      "selected":true,

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

Output of show version

admin@xxxxxxx:~$ show version

SONiC Software Version: SONiC.20240510.18
SONiC OS Version: 12
Distribution: Debian 12.6
Kernel: 6.1.0-22-2-amd64
Build commit: a29e50aa51
Build date: Sat Dec 14 03:12:35 UTC 2024
Built by: azureuser@5c74dcafc000000

Platform: x86_64-arista_720dt_48s
HwSKU: Arista-720DT-G48S4
ASIC: broadcom
ASIC Count: 1
Serial Number: WTW23380751
Model Number: CCS-720DT-48S-2F
Hardware Revision: 03.00
Uptime: 11:39:02 up 14:47,  1 user,  load average: 0.81, 0.90, 0.81
Date: Wed 18 Dec 2024 11:39:02

Docker images:
REPOSITORY                 TAG           IMAGE ID       SIZE
docker-mux                 20240510.18   2200e4fed9e2   366MB
docker-mux                 latest        2200e4fed9e2   366MB
docker-sonic-telemetry     20240510.18   ae791d1735de   380MB
docker-sonic-telemetry     latest        ae791d1735de   380MB
docker-dhcp-server         latest        a1daad24d1da   338MB
docker-macsec              latest        d82ed22d7ce9   345MB
docker-eventd              20240510.18   0538ed3383ad   314MB
docker-eventd              latest        0538ed3383ad   314MB
docker-sonic-gnmi          20240510.18   2f4f75b7daf5   380MB
docker-sonic-gnmi          latest        2f4f75b7daf5   380MB
docker-gbsyncd-broncos     20240510.18   929679e962c4   352MB
docker-gbsyncd-broncos     latest        929679e962c4   352MB
docker-gbsyncd-credo       20240510.18   e481420a023a   326MB
docker-gbsyncd-credo       latest        e481420a023a   326MB
docker-orchagent           20240510.18   a433b9332419   356MB
docker-orchagent           latest        a433b9332419   356MB
docker-teamd               20240510.18   01e8fef50250   343MB
docker-teamd               latest        01e8fef50250   343MB
docker-fpm-frr             20240510.18   6f69fe113aa4   368MB
docker-fpm-frr             latest        6f69fe113aa4   368MB
docker-dhcp-relay          latest        d23e91390d63   326MB
docker-platform-monitor    20240510.18   adb8a8554a63   434MB
docker-platform-monitor    latest        adb8a8554a63   434MB
docker-snmp                20240510.18   c2d3f0ca3d4c   354MB
docker-snmp                latest        c2d3f0ca3d4c   354MB
docker-lldp                20240510.18   ae4caa548cf8   360MB
docker-lldp                latest        ae4caa548cf8   360MB
docker-database            20240510.18   0e1b52511adc   323MB
docker-database            latest        0e1b52511adc   323MB
docker-acms                20240510.18   f9d894bd99b8   365MB
docker-acms                latest        f9d894bd99b8   365MB
docker-router-advertiser   20240510.18   f0bcc1cd89e2   315MB
docker-router-advertiser   latest        f0bcc1cd89e2   315MB
docker-sonic-restapi       20240510.18   0df48b512c09   333MB
docker-sonic-restapi       latest        0df48b512c09   333MB
docker-syncd-brcm          20240510.18   7e2a83355b40   742MB
docker-syncd-brcm          latest        7e2a83355b40   742MB
k8s.gcr.io/pause           3.5           ed210e3e4a5b   683kB