update least_time LB method availability for NGINX OSS

[yogarajalakshmi-s]

Proposed changes

NGINX Open Source v1.31.0 added least_time HTTP load balancing, previously Plus-only. This PR updates the docs to reflect that all least_time variants are now available in OSS: removes the Plus-only callout in upstream-settings.md, removes the Load balancing methods bullet from nginx-plus.md, and removes Plus-only labels from http-load-balancer.md. Stream least_time (TCP/UDP) remains Plus-only and is unchanged. This PR is related to nginx/nginx-gateway-fabric#5381

This PR fixes #2026

Checklist

Before sharing this pull request, I completed the following checklist:

• I read the Contributing guidelines
• My branch adheres to the Git conventions
• My content changes adhere to the F5 Technical Writing Style Guide
• If my changes involve potentially sensitive information¹, I have assessed the possible impact
• I have waited to ensure my changes pass tests, and addressed any discovered issues

Footnotes

1. Potentially sensitive information includes personally identify information (PII), authentication credentials, and live URLs. Refer to the style guide for guidance about placeholder content. ↩

[bjee19]

Hey @yogarajalakshmi-s, thanks for opening this PR. Do you mind rebasing the targeted branch to be ngf-release-2.7, since PRs that go into main are automatically deployed into the production site, and how the production site only reflects NGF's latest release's content, merging to main won't be an accurate representation of that.

The addition on the NGF side won't be available until the 2.7 release so we want to keep the docs site matching that. When we release NGF's 2.7, we merge the ngf-release-2.7 into main. Might be a little troublesome so feel free to open up a new PR if needed.

[yogarajalakshmi-s]

Hey @yogarajalakshmi-s, thanks for opening this PR. Do you mind rebasing the targeted branch to be ngf-release-2.7, since PRs that go into main are automatically deployed into the production site, and how the production site only reflects NGF's latest release's content, merging to main won't be an accurate representation of that.

The addition on the NGF side won't be available until the 2.7 release so we want to keep the docs site matching that. When we release NGF's 2.7, we merge the ngf-release-2.7 into main. Might be a little troublesome so feel free to open up a new PR if needed.

Done! Rebased onto ngf-release-2.7 and force-pushed. Sorry for the mix-up in between.