Track 8.19 branch instead of 8.x for jdk compat tests

[donoghuc]

Release notes

[rn:skip]

What does this PR do?

The 8.x branch has been renamed 8.19. Reflect this in jdk test config.

Why is it important/What is the impact to the user?

N/A

Checklist

• [ ] My code follows the style guidelines of this project
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ ] I have made corresponding change to the default configuration files (and/or docker env variables)
• [ ] I have added tests that prove my fix is effective or that my feature works

[mergify]

This pull request does not have a backport label. Could you fix it @donoghuc? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-8./d is the label to automatically backport to the 8./d branch. /d is the digit.
• If no backport is necessary, please add the backport-skip label

[mashhurs]

LGTM~

[elastic-sonarqube]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarQube

[donoghuc]

@mashhurs do we backport changes to catalog-info.yaml?

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 98755bb

[mashhurs]

@mashhurs do we backport changes to catalog-info.yaml?

It doesn't seem so.
As we can see JDK pipeline runs on main (with its catalof-info.yaml) on two: main & 8.x (with your change it will be 8.19) branches.
With your question I realise we need to also add 9.x (current 9.0 is almost identical with main, I have added in my TODO to add 9.x when we cut).

So, from current situation, your change is sufficient.

[donoghuc]

That makes sense. OK, I added "backport-skip" label to this. I'll merge and let you handle adding the 9 series to the matrix separately. Thanks!