Update running-logstash-kubernetes.asciidoc

[flexitrev]

Just removing tech preview language

[github-actions]

📃 DOCS PREVIEW ✨ https://logstash_bk_16909.docs-preview.app.elstc.co/diff

[mergify]

This pull request does not have a backport label. Could you fix it @flexitrev? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-8./d is the label to automatically backport to the 8./d branch. /d is the digit.
• backport-8.x is the label to automatically backport to the 8.x branch.

[mergify]

backport-8.x has been added to help with the transition to the new branch 8.x.
If you don't need it please use backport-skip label.

[mergify]

This pull request is now in conflicts. Could you fix it @flexitrev? 🙏
To fixup this pull request, you can check out it locally. See documentation: https://help.github.com/articles/checking-out-pull-requests-locally/

git fetch upstream
git checkout -b ls-k8s-doc upstream/ls-k8s-doc
git merge upstream/main
git push upstream ls-k8s-doc