Refactor(eos_cli_config_gen): Add default: default for ip_name_servers[].vrf

[laxmikantchintakindi]

Enhancement summary

Add default: default for ip_name_servers[].vrf

Which component of AVD is impacted

eos_cli_config_gen

Use case example

site3-leaf1(config)#show run se name-ser
ip name-server vrf MGMT 10.14.0.1
ip name-server vrf MGMT 192.168.17.1
ip name-server vrf default 1.1.1.1

when there is no vrf configured, eos adds default keyword for vrf.

Describe the solution you would like

Add default: default for ip_name_servers[].vrf

Describe alternatives you have considered

No response

Additional context

No response

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