vpp: Ignore NO_SUCH_ENTRY in ip_neigh_delete

[yue-fred-gao]

why

when interface is shut, vpp automatically removes the dynamic nexthops over the interface. orchagent also deletes the nexthops over the interface. When vpp calls vl_api_ip_neighbor_add_del_t api to delete the neighbours, vpp returns NO_SUCH_ENTRY. saivpp should ignore the error.

what this PR does

1. move all the log messages from handler to the corresponding API calls. This is because the handler doesn't have enough context (delete or add) to ignore the error.
2. Ignore NO_SUCH_ENTRY for delete operations.
3. Ignore ROUTE_ENTRY update if packet action is SAI_PACKET_ACTION_FORWARD but missing SAI_ROUTE_ENTRY_ATTR_NEXT_HOP_ID. This is possible in bulk_set like below. See the first entry.

20.07:04:19.106477|S|SAI_OBJECT_TYPE_ROUTE_ENTRY||{"dest":"0.0.0.0/0","switch_id":"oid:0x21000000000000","vr":"oid:0x3000000000002"}|SAI_ROUTE_ENTRY_ATTR_PACKET_ACTION=SAI_PACKET_ACTION_FORWARD||{"dest":"0.0.0.0/0","switch_id":"oid:0x21000000000000","vr":"oid:0x3000000000002"}|SAI_ROUTE_ENTRY_ATTR_NEXT_HOP_ID=oid:0x40000000000f4||{"dest":"::/0","switch_id":"oid:0x21000000000000","vr":"oid:0x3000000000002"}|SAI_ROUTE_ENTRY_ATTR_PACKET_ACTION=SAI_PACKET_ACTION_FORWARD||{"dest":"::/0","switch_id":"oid:0x21000000000000","vr":"oid:0x3000000000002"}|SAI_ROUTE_ENTRY_ATTR_NEXT_HOP_ID=oid:0x40000000000f5

[mssonicbld]

/azp run

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[mssonicbld]

/azp run

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[mssonicbld]

/azp run

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[mssonicbld]

Cherry-pick PR to msft-202603: Azure/sonic-sairedis.msft#124