hermes: Metrics endpoint does not expose `wallet_balance` metric

Summary of Bug

You can see that we can get wallet_balance via metrics as written in hermes docs.

However, in our current implementation of hermes, metrics does not have a wallet_balance gauge.

Is there any code change that is different from the docs? Please comment.

# HELP wallet_balance The balance of each wallet Hermes uses per chain. Please note that when converting the balance to f64 a loss in precision might be introduced in the displayed value # TYPE wallet_balance gauge wallet_balance{account="cosmos1340jyu3hawjzusu4jfwh29prpglkju5rlkpesn",chain="ibc-1",denom="stake",service_name="unknown_service",otel_scope_name="hermes",otel_scope_version=""} 99994729 wallet_balance{account="cosmos1fk5ykcvkgr4yzlzfyegnaaqyc0ulv8wv8u9hjl",chain="ibc-3",denom="stake",service_name="unknown_service",otel_scope_name="hermes",otel_scope_version=""} 100000000 wallet_balance{account="cosmos1j6z6q9d2gf2suav88z8g3zf726vz9ehg4hkr8x",chain="ibc-0",denom="stake",service_name="unknown_service",otel_scope_name="hermes",otel_scope_version=""} 99993392 wallet_balance{account="cosmos1yxzuet72f4qlks8tzrna6y2q4wchur02gqs5al",chain="ibc-2",denom="stake",service_name="unknown_service",otel_scope_name="hermes",otel_scope_version=""} 100000000

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