[yang] Yang validation throws error while validating snmp agent address

[dgsudharsan]

Description

Issue was seen after the integration of #15587
All commands that use yang thrown the below error

sudo sonic-package-manager list
libyang[1]: Default value "" in the list key "port" is ignored. (/sonic-snmp:sonic-snmp/SNMP_AGENT_ADDRESS_CONFIG/SNMP_AGENT_ADDRESS_LIST)
libyang[1]: Default value "" in the list key "vrf_name" is ignored. (/sonic-snmp:sonic-snmp/SNMP_AGENT_ADDRESS_CONFIG/SNMP_AGENT_ADDRESS_LIST)
Name            Repository                   Description                   Version    Status
--------------  ---------------------------  ----------------------------  ---------  ---------
database        docker-database              SONiC database package        1.0.0      Built-In
dhcp-relay      docker-dhcp-relay            N/A                           1.0.0      Installed
eventd          docker-eventd                SONiC eventd package          1.0.0      Built-In
fpm-frr         docker-fpm-frr               SONiC fpm-frr package         1.0.0      Built-In
lldp            docker-lldp                  SONiC lldp package            1.0.0      Built-In
macsec          docker-macsec                N/A                           1.0.0      Installed
mgmt-framework  docker-sonic-mgmt-framework  SONiC mgmt-framework package  1.0.0      Built-In
mux             docker-mux                   SONiC mux package             1.0.0      Built-In
nat             docker-nat                   SONiC nat package             1.0.0      Built-In
p4rt            docker-sonic-p4rt            SONiC p4rt package            1.0.0      Built-In
pmon            docker-platform-monitor      SONiC pmon package            1.0.0      Built-In
radv            docker-router-advertiser     SONiC radv package            1.0.0      Built-In
sflow           docker-sflow                 SONiC sflow package           1.0.0      Built-In
snmp            docker-snmp                  SONiC snmp package            1.0.0      Built-In
swss            docker-orchagent             SONiC swss package            1.0.0      Built-In
syncd           docker-syncd-mlnx            SONiC syncd package           1.0.0      Built-In
teamd           docker-teamd                 SONiC teamd package           1.0.0      Built-In
telemetry       docker-sonic-telemetry       SONiC telemetry package       1.0.0      Built-In

Steps to reproduce the issue:

1. Install latest sonic master image
2. Run sonic-package-manager list

Describe the results you received:

libyang shouldn't throws trace messages

Describe the results you expected:

libyang shouldn't thrown any trace

Output of show version:

(paste your output here)

Output of show techsupport:

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

[neethajohn]

Same as 16011