[SLO][Fleet] Reauthorize SLO transforms

[mgiota]

Summary

As part of this PR a secondary authorization header was added to Transforms in Fleet, making the permissions/privileges dependent on the logged-in user. Previously everything was installed as kibana_system user, which has limited permissions to a specific set of indices defined internally.

When SLO assets are installed, transforms get installed as well. The secondary authorization header that was added to Transforms in Fleet, didn't automatically got applied to SLO transforms, since SLO assets are installed as kibana assets and the secondary authorization header is currently applied only to ES assets.

Thus in this PR which handles the installation of SLO assets in Fleet, we hit following permission error:

✅ Acceptance criteria

Adapt the SLO installation process to incorporate the Transform reauthorization process

[mgiota]

I created a temp commit branched from this PR. I adapted existing Transforms Reauthorization process to take into consideration SLO transforms as well. Here's how the Reauthorization workflow looks like so far:

Screen.Recording.2024-08-01.at.16.40.39.mov

This is still WIP, since I am clarifying the workflow with Fleet team in this thread

cc @qn895

[elasticmachine]

Pinging @elastic/obs-ux-management-team (Team:obs-ux-management)

[kdelemme]

I think we don't want to pursue this. @jasonrhodes can I close?

[jasonrhodes]

Yes we should close, as we are not installing SLOs via integrations. This is what is supposed to be replaced by "templates" or "prepackaged assets", or whatever those end up being called. I'll link that issue to this one.