revisit usage of version.stack

[shainaraskas]

inspired by #2222

we are using {{version.stack}} in the same way we used it in the old versioned docs in some cases.

this doesn't make sense in the new system, because it implies that something is only true in the latest version, when it might have been true since the base version

example: https://github.com/elastic/docs-content/pull/2222/files#diff-07f5858632ade331374d8096f51946affacd54bd741f04658a5288db4c879a13

most areas for concern I believe are in the dev docs zone but we probably all need to audit this ... might apply to other version variables as well

[eedugon]

For the moment I've added this to Team:Developer, but also added a cross-team label, just in case we need to assign this issue to another team or create a sub-issue for another team.