Remove PeerFinder request timeout

[DaveCTurner]

There's really no need to time out so enthusiastically here, we can wait
for as long as it takes to receive a list of other discovery targets
from the remote peer. This commit removes the timeout, deferring failure
detection down to the TCP level (e.g. keepalives) as managed by the OS.

Relates #132713, #123568

[elasticsearchmachine]

Pinging @elastic/es-distributed-coordination (Team:Distributed Coordination)

[github-actions]

🔍 Preview links for changed docs

• docs/reference/elasticsearch/configuration-reference/discovery-cluster-formation-settings.md

[github-actions]

ℹ️ Important: Docs version tagging

👋 Thanks for updating the docs! Just a friendly reminder that our docs are now cumulative. This means all 9.x versions are documented on the same page and published off of the main branch, instead of creating separate pages for each minor version.

We use applies_to tags to mark version-specific features and changes.

Expand for a quick overview

When to use applies_to tags:

✅ At the page level to indicate which products/deployments the content applies to (mandatory)
✅ When features change state (e.g. preview, ga) in a specific version
✅ When availability differs across deployments and environments

What NOT to do:

❌ Don't remove or replace information that applies to an older version
❌ Don't add new information that applies to a specific version without an applies_to tag
❌ Don't forget that applies_to tags can be used at the page, section, and inline level

🤔 Need help?

• Check out the cumulative docs guidelines
• Reach out in the #docs Slack channel

[ywangd]

Changes look good to me. I have just a logistic question.

[ywangd]

This is a deprecation and strictly speaking behaviour change. Do we want to use a different label other than >non-issue?

[DaveCTurner]

Ok I marked it >deprecation and added a changelog.

[elasticsearchmachine]

Hi @DaveCTurner, I've created a changelog YAML for you. Note that since this PR is labelled >deprecation, you need to update the changelog YAML to fill out the extended information sections.

[ywangd]

LGTM