avalanche: add firewood profile for mainnet (pruning-free merkle DB)

Add new avalanchego v1.14.2 profile with Firewood state database backend:
- state-scheme: firewood (with required populate-missing-tries:null, snapshot-cache:0)
- state-sync-enabled: true (confirmed supported in v1.14.2)
- chain-config-dir: /config/firewood
- db-type: firewood
- coreth-state-scheme: firewood

Generated compose: avalanche-mainnet-go-firewood-firewood.yml

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

reference-rpc-endpoint.json

@@ -3441,6 +3441,7 @@
     "syncing_lag": 40,
     "urls": [
       "https://rpc.testnet.chain.robinhood.com/rpc",
+      "https://robinhood-sepolia-rpc.publicnode.com",
       "https://robinhood-testnet.drpc.org"
     ]
   },