feat: add flag to exclude networks from using infura for live balance

[jpuri]

Explanation

Add flag to exclude networks from using infura for live balance.
It is needed primarily for Monad, related to PR: #8839

References

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

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Note

Medium Risk
Changes which RPC endpoint validates live balances before pay quotes/submit; misconfigured flags could cause wrong or failed balance reads on affected chains.

Overview
Adds remote feature flag confirmations_pay_extended.excludeChainIdsFromInfura so specific chains can opt out of preferring Infura for live on-chain balance RPCs (e.g. Monad).

Introduces isChainExcludedFromInfura (case-insensitive chain ID match) and wires getLiveTokenBalance to pass preferInfura: false when the chain is listed, so balance queries use the default network client instead of forcing the Infura endpoint. Behavior is unchanged for chains not in the list.

Unit tests cover the flag helper and Infura skip/use paths in live balance fetching; the package changelog documents the change.

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