Add documentation for managing ECK file-based password length.

[naemono]

The following elastic/cloud-on-k8s#8817 is planned to be released with the ECK 3.2/Stack 9.2 release.

(replaces #3322 as it was based of the wrong branch)

[github-actions]

🔍 Preview links for changed docs

• deploy-manage/deploy/cloud-on-k8s/configure-eck.md
• deploy-manage/users-roles/cluster-or-deployment-auth/managed-credentials-eck.md

[eedugon]

LGTM!
I have suggested to place the applies_to right after the heading, and not after the initial note.

[shainaraskas]

looks really good. I think we want to consider relocating this chunk of info though because it's specific to the file realm. would you consider making it an H4 under the File realm heading?

https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/3339/deploy-manage/users-roles/cluster-or-deployment-auth/managed-credentials-eck#file-realm

[shainaraskas]

probably ok outside of a note

Suggested change

	:::{note}
	Changing these values does not update existing passwords. To rotate current credentials, refer to the [rotating credentials documentation](#k8s-rotate-credentials)
	:::
	Changing these values does not update existing passwords. To rotate current credentials, refer to the [rotating credentials documentation](#k8s-rotate-credentials)

[shainaraskas]

I think we want this to not be two notes in a trenchcoat

Suggested change

	The ability to control the length of passwords for [file-based credentials](/deploy-manage/users-roles/cluster-or-deployment-auth/file-based.md) generated by {{eck}} requires an Enterprise license.
	The ability to control the length of passwords for [file-based credentials](/deploy-manage/users-roles/cluster-or-deployment-auth/file-based.md) generated by {{eck}} requires an Enterprise license.
	:::

[shainaraskas]

(+ approving to unblock)

(oops, guess this tab was old and edu already got you)