Remove apm_user role

[sorenlouv]

Meta issue: elastic/kibana#116760
The apm_user role was marked as deprecated in 7.13 and was supposed to be removed in 8.0.
All mentions of apm_user role was finally removed in elastic/kibana#132790 and this PR removes the actual role

[elasticsearchmachine]

@sqren please enable the option "Allow edits and access to secrets by maintainers" on your PR. For more information, see the documentation.

[elasticsearchmachine]

Hi @sqren, I've created a changelog YAML for you. Note that since this PR is labelled >breaking, you need to update the changelog YAML to fill out the extended information sections.

[sorenlouv]

I added the >breaking label since this is technically a breaking change. OTOH the role was deprecated over a year ago, and the role was supposed to have been removed in 8.0. Finally removing it can be seen as an implementation detail.

[elasticsearchmachine]

Hi @sqren, I've updated the changelog YAML for you. Note that since this PR is labelled >deprecation, you need to update the changelog YAML to fill out the extended information sections.

[ywangd]

@sqren IIUC, the apm_user role was meant to be removed in 8.0, but we forgot to do so? If that's true, I think now it needs to go through the breaking change committee first for future removal in (possibly) 9.0.

[sorenlouv]

@ywangd Yes we forgot to remove it in 8.0 (and there were no good alternatives available at the time). Now we are recommending users to use editor and viewer roles instead.
For this reason it's probably a better idea to remove it in 9.0 even though it's been deprecated since 7.13.

I'll update the PR to do that. Does it still need to go through the breaking change committee if we move the removal to 9.0?

[ywangd]

Does it still need to go through the breaking change committee if we move the removal to 9.0?

Yes. We have a similar case and it needed to go through the committe. I'll tag you on the issue.

I'll update the PR to do that.

It's hard to do that now since we don't have a 9.0 branch yet.

[sorenlouv]

Replaced by #87674