fix: use latest out tx for all checks

[kaladinlight]

Description

Follow up on: #6813

checkOutboundTxConfirmations was still using out_txs[0] instead of latestOutTx, so this change ensures everything is using the same out tx for status checks.

Pull Request Type

• 🐛 Bug fix (Non-breaking Change: Fixes an issue)
• 🛠️ Chore (Non-breaking Change: Doc updates, pkg upgrades, typos, etc..)
• 💅 New Feature (Breaking/Non-breaking Change)

Issue (if applicable)

N/A

Risk

High Risk PRs Require 2 approvals

Medium - changes logic surrounded status updates for swaps

What protocols, transaction types or contract interactions might be affected by this PR?

Thorchain

Testing

See #6813

Engineering

☝️

Operations

☝️

Screenshots (if applicable)

[gomesalexandre]

Looks sane to me - tested locally:

L1 -> RUNE

RUNE -> L1

L1 -> L1