Updates "Cloud native security" to "Cloud security"

[benironside]

Fixes #6170 — minor changes on several pages. We are no longer providing only "Native" cloud security (we're using 3rd party data as well as providing our own integrations). This PR updates language on several pages accordingly. Please refer to the diff for changes.

[github-actions]

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[mergify]

This pull request is now in conflicts. Could you fix it @benironside? 🙏
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 6170-cloudsec-section-titleupdate upstream/6170-cloudsec-section-titleupdate
git merge upstream/main
git push upstream 6170-cloudsec-section-titleupdate

[natasha-moore-elastic]

There's a reference to "cloud native security" on line 5 of the Elastic Security overview page (ESS) and line 7 of the same serverless page. Not sure if these need to be updated too – approving in case they don't.

[jmikell821]

Hi @benironside just confirming that Security doesn't need to be capitalized? We have our Elastic Security product name as well as AI for Security as an H1. Nitpicking here, but would be good to be consistent, IMO.