Minor tweaks to caching

[timja]

I was having a look at the latest version of this plugin after deploying it to ci.jenkins.io.

I noticed that the allSteps call was being cached although the build was running:

https://ci.jenkins.io/job/Core/job/jenkins/job/PR-10186/13/pipeline-overview/?selected-node=186

I couldn't reproduce it locally but I'm guessing it was a timing issue.

I've moved some pieces out of guessing based on state and used the flag to check it on the run.
I've also switching from inProgress to isBuilding which does an additional check to make sure the build has started.

This may not fix the issue as I didn't hit it locally.

Testing done

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests that demonstrate the feature works or the issue is fixed

[felipecrs]

I also have had complaints from users that steps aren't showing up for certain builds, whereas they show up in private tabs.

These complaints aren't very solid as it's very difficult to reproduce them, but I would appreciate if you can merge this.

I can then ask my users to keep monitoring on whether it happens again.

[timja]

I also have had complaints from users that steps aren't showing up for certain builds, whereas they show up in private tabs.

These complaints aren't very solid as it's very difficult to reproduce them, but I would appreciate if you can merge this.

I can then ask my users to keep monitoring on whether it happens again.

Thanks for letting me know that, it'll only help for new builds, (unless they force refresh to clear the cache).