Make wolfi 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

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

[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.