Make ubi the default image and drop the ubuntu-based image

[kruskall]

We've released chainguard image in #13137

Since 8.15.0 we're publishing both apm-server and apm-server-wolfi apm-server-ubi

In future relase we should drop the ubuntu based image and make wolfi ubi the default image, thus only maintaining a apm-server image based on wolfi ubi.

[cachedout]

@simitt Per my discussion with @mgreau today, it seems like this work will need to be done by approximately the end of October if not sooner. (@mgreau please correct me if that's not correct in your view.)

[simitt]

@mgreau @cachedout please confirm in which stack version we are supposed to actually drop ubuntu support and switch the default.

[cachedout]

@simitt Did this question get adequately answered via the Slack discussion in the or do you want more clarity in this issue?

[simitt]

We have everything we need, thank you.

[kruskall]

ECK has been updated and the default image is based on ubi.

the unified release needs to be updated to stop producing ubi images but there's nothing we can do with that. Closing this since the work on our side is done