Supported OS smoke tests fail when version bumps take place

[marclop]

Description

The supported OS tests fail every time the stack version is bumped and the unified snapshot build hasn't (yet) run, which results in the SNAPSHOT version not being available. Ideally, we should have some sort of mechanism in place that avoids this from happening.

 Error: failed to obtain a stack version matching "8.15.4-SNAPSHOT": please specify a valid version_regex

Possible solutions

A potential solution would be to query ESS for the available SNAPSHOT versions, since if a stack pack is published in ESS, then it must also be available in the actual artifacts, but there may be some other better ways to do this.

Occurrences

• https://github.com/elastic/apm-server/actions/runs/11396764001/job/31711155642