fix(snmp): fix sa_08 test failure due to outdated snmp_generator schema and missing MIB

Problem

The sa_08-VNF With VNF Indicators SNMP Robot test suite has been failing deterministically in the Jenkins daily build. Two test cases fail:

• Instantiate Network Service
• Get VNF SNMP Metrics

Root cause:

level=error msg="Error generating config netsnmp"
err="error parsing yml config: yaml: unmarshal errors:
     line 13: field auth not found in type main.plain"

Root Cause Analysis

Since snmp_exporter v0.24.0, the auth field was removed from modules and moved to a top-level auths section. The generator.yml still used the old inline schema, causing generate_snmp Day-1 primitive to fail and the NS to reach BROKEN state.

Changes

1. Migrate generator.yml to auths top-level schema — fixes generate_snmp failure
2. Add missing HCNUM-TC MIB — required by IF-MIB for 64-bit counters
3. Upgrade snmpexporter runtime to v0.30.1 + add auth param to prometheus-job-template.j2
4. Upgrade install.sh to Go 1.26.4 + snmp_generator v0.30.1
5. Migrate init-container seed snmp.yml to auths/modules schema (was 20k-line flat pre-v0.24 config causing CrashLoopBackOff with v0.30.1 runtime)

Verification — E2E on ephemeral ETSI VM (Jenkins build #536, 2026-06-16)

NS instantiation — COMPLETED

| sa_08-test | 9a4d5185-9802-4bb8-a138-4e69d29019b6 | READY | IDLE (None) | N/A |
| 8b2d8d08   | instantiate | COMPLETED | 2026-06-16T21:26:12 |

Pod status — Running 2/2, no CrashLoopBackOff

NAME                   READY   STATUS    RESTARTS   AGE
eechart-0030788334-0   2/2     Running   1          9m3s

snmp.yml generated correctly by generate_snmp Day-1 primitive

# WARNING: This file was auto-generated using snmp_exporter generator
auths:
  osm_auth:
    community: public
    security_level: noAuthNoPriv
    version: 2
modules:
  osm-snmp:
    walk:
    - 1.3.6.1.2.1.2
    metrics:
    - name: ifInOctets
      oid: 1.3.6.1.2.1.2.2.1.10
      type: counter
    - name: ifMtu
      oid: 1.3.6.1.2.1.2.2.1.4
      type: gauge

Prometheus metrics — ifInOctets and ifMtu present with real values

{"status":"success","data":{"resultType":"vector","result":[
  {"metric":{"__name__":"ifInOctets","ifAlias":"VyOS-eth0","ifIndex":"2","ifName":"eth0","instance":"172.21.249.162"},"value":[1781645717,"110716"]},
  {"metric":{"__name__":"ifMtu","ifAlias":"VyOS-eth0","ifIndex":"2","ifName":"eth0","instance":"172.21.249.162"},"value":[1781645446,"1500"]}
]}}

All three failure points resolved and verified on ephemeral ETSI environment:

• Fix 1: snmpexporter starts without CrashLoopBackOff (seed schema migrated)
• Fix 2: NS reaches READY, generate_snmp COMPLETED (generator.yml schema migrated)
• Fix 3: ifInOctets and ifMtu available in Prometheus (auth param added to job template)