feat: curio: Use Yugabyte's PGX driver

[snadrus]

Related Issues

This enables load balancing and failover in a Yugabyte-standard way.

Proposed Changes

Use yugabyte's pgx/v5 instead of the default pgx.
Note: Get() was removed as it is duplicates functionality available with less code.

Additional Info

Checklist

Before you mark the PR ready for review, please make sure that:

• Commits have a clear commit message.
• PR title is in the form of of <PR type>: <area>: <change being made>
  • example: fix: mempool: Introduce a cache for valid signatures
  • PR type: fix, feat, build, chore, ci, docs, perf, refactor, revert, style, test
  • area, e.g. api, chain, state, market, mempool, multisig, networking, paych, proving, sealing, wallet, deps
• If the PR affects users (e.g., new feature, bug fix, system requirements change), update the CHANGELOG.md and add details to the UNRELEASED section.
• New features have usage guidelines and / or documentation updates in
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  • Discussion Tutorials
• Tests exist for new functionality or change in behavior
• CI is green