Add idletimeout for http connection on evm endpoint

[RogerKSI]

Fixed: #XXXX

Implementation details

Please ensure the following requirements are met before submitting a pull request:

• The pull request is targeted against the correct target branch
• The pull request is linked to an issue with appropriate discussion and an accepted design OR is linked to a spec that describes the work.
• The pull request includes a description of the implementation/work done in detail.
• The pull request includes any and all appropriate unit/integration tests
• You have added a relevant changelog entry to CHANGELOG_UNRELEASED.md
• You have re-reviewed the files affected by the pull request (e.g. using the Files changed tab in the Github PR explorer)

[Copilot]

Pull request overview

Adds a custom dial path for EVM RPC endpoints to proactively close idle HTTP keep-alive connections (to reduce stale-connection resets commonly caused by load balancers).

Changes:

• Introduce dialEVMEndpoint() to use a custom http.Transport with a shorter IdleConnTimeout for HTTP/HTTPS endpoints.
• Switch Connect() to use dialEVMEndpoint(ctx, endpoint) instead of ethclient.Dial(endpoint).

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.