Deprecate /_xpack/security/* in favor of /_security/*

[jkakavas]

This commit is part of our plan to deprecate and ultimately
remove the use of _xpack in the REST APIs. It includes:

• Adjusted REST api docs
• Adjusted HLRC docs and doc tests
• Adjusted REST actions with deprecation warnings
• Changed endpoints in rest-api-spec and relevant file names

Relates #35958

[elasticmachine]

Pinging @elastic/es-core-infra

[jkakavas]

I've seen the rest of the PRs are not touching the file names for these, but it made sense to me. No problem to revert if there are objections though.

[jkakavas]

elasticsearch-ci-1 failed with an error in testIndexFollowing that doesn't reproduce locally

./gradlew :client:rest-high-level:integTestRunner -Dtests.seed=C6BDD3AC7F18F9C1 -Dtests.class=org.elasticsearch.client.CCRIT -Dtests.method="testIndexFollowing" -Dtests.security.manager=true -Dtests.locale=de -Dtests.timezone=Africa/Tunis -Dcompiler.java=11 -Druntime.java=8

giving it another go:
run the gradle build tests 1

[jasontedor]

LGTM assuming that CI goes green.

[jkakavas]

@jasontedor pinging to see if you want to take a look at a509387 which adds back a number of api definitions in the deprecated format in order to use these against the old cluster in rolling upgrade tests. I couldn't think of a more elegant way to do this

[jasontedor]

@jkakavas I have a different idea, let's backport the new endpoints to 6.x (without all the other changes to the docs, specification, etc.). What do you think of this approach?

[droberts195]

The idea of backporting the new endpoints to 6.x would be consistent with what watcher is doing in #36269 (although in that case it already did support the new endpoints albeit deprecated!) and what ML is doing in #36373. I think backporting the new endpoints is also nice because it means customers have the option to avoid deprecation warnings in the mixed version cluster during a rolling upgrade from 6.last to 7.x by switching clients to the new endpoints before starting the rolling upgrade.

[jkakavas]

Thanks folk, that definitely makes sense. I'll backport the endpoints and then revert the changes here to ensure a green CI

[jasontedor]

Thanks @jkakavas.

[jasontedor]

LGTM.

[jkakavas]

@jasontedor any objections to me re-introducing ff242e8 so that we don't backport _security endpoints to 6.5 too for Full Cluster restart tests ?

[jasontedor]

Yeah, for full cluster restart that is fine because we test against very old clusters where we can't backport anything so that we have to take the if/else route.

[jkakavas]

@elasticmachine test this please

[jkakavas]

@elasticmachine test this please

[jasontedor]

@elasticmachine run gradle build tests 1 and run gradle build tests 2

[jkakavas]

elasticserach-ci-tests-2 was failing because of a typo in #36379 that I corrected in 9bf0999, and elasticserach-ci-tests-1 needed additional changes for put role that was merged while this PR was fighting with CI.

🤞