[YANG][Bugfix] Fix incorrect pattern of nexthop-vrf in sonic-static-route.yang

[puffc]

Why I did it

Fix issue #21352
According to the Static Route HLD, the nexthop-vrf field should be optional:

;Defines IP static route  table
;
;Status: stable

key                 = STATIC_ROUTE|vrf-name|prefix ;
vrf-name            = 1\*15VCHAR ; VRF name
prefix              = IPv4Prefix / IPv6prefix
nexthop             = string; List of gateway addresses;
ifname              = string; List of interfaces
distance            = string; {0..255};List of distances.
                      Its a Metric used to specify preference of next-hop
                      if this distance is not set, default value 0 will be set when this field is not configured for nexthop(s)
nexthop-vrf         = string; list of next-hop VRFs. It should be set only if ifname or nexthop IP  is not
                      in the current VRF . The value is set to VRF name
                      to which the interface or nexthop IP  belongs for route leaks.
blackhole           = string; List of boolean; true if the next-hop route is blackholed.
                      Default value false will be set when this field is not configured for nexthop(s)

However, in the sonic-static-route.yang the pattern of nexthop-vrf implies the nexthop-vrf is mandatory.

sonic-static-route.yang:
...
...
        leaf nexthop-vrf {
          type string {
            pattern "(((Vrf[a-zA-Z0-9_-]+)|(default)|(mgmt)),)*((Vrf[a-zA-Z0-9_-]+)|(default)|(mgmt))";
          }
          description
            "VRF name of the nexthop. This is for vrf leaking";
...

Work item tracking

• Microsoft ADO (number only):

How I did it

Correct the pattern of nexthop-vrf.

How to verify it

admin@sonic:~$ sudo config route add prefix 0.0.0.0/0 nexthop 172.16.0.3
admin@sonic:~$ redis-cli -n 4
127.0.0.1:6379[4]> key *STATIC*
(error) ERR unknown command 'key', with args beginning with: '*STATIC*'
127.0.0.1:6379[4]> keys *STATIC*
1) "STATIC_ROUTE|default|0.0.0.0/0"
127.0.0.1:6379[4]> hgetall "STATIC_ROUTE|default|0.0.0.0/0"
 1) "blackhole"
 2) "false"
 3) "distance"
 4) "0"
 5) "ifname"
 6) ""
 7) "nexthop"
 8) "172.16.0.3"
 9) "nexthop-vrf"
10) ""
127.0.0.1:6379[4]> exit
admin@sonic:~$ sudo config interface breakout Ethernet8 4x100G -yf

Running Breakout Mode : 1x400G
Target Breakout Mode : 4x100G

Ports to be deleted :
 {
    "Ethernet8": "400000"
}
Ports to be added :
 {
    "Ethernet8": "100000",
    "Ethernet10": "100000",
    "Ethernet12": "100000",
    "Ethernet14": "100000"
}
Breakout process got successfully completed.
Please note loaded setting will be lost after system reboot. To preserve setting, run `config save`.

Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006
• 202012
• 202106
• 202111
• 202205
• 202211
• 202305
• 202405
• 202411

Tested branch (Please provide the tested image version)

Description for the changelog

Link to config_db schema for YANG module changes

A picture of a cute animal (not mandatory but encouraged)

[mssonicbld]

/azp run Azure.sonic-buildimage

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[mssonicbld]

/azp run Azure.sonic-buildimage

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[mssonicbld]

/azp run Azure.sonic-buildimage

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[puffc]

@UmaMaven @dgsudharsan @qiluo-msft Please review, Thanks.

[dgsudharsan]

@qiluo-msft @prsunny Can you please review?

[dprital]

@kperumalbfn , Can you please cherry pick to 202411 ?

[mssonicbld]

Cherry-pick PR to 202411: #21705