jjbb: enable 8.1 and disable 7.16

[v1v]

What does this PR do?

7.16 is not an active branch.
8.1 is an active branch.

Why is it important?

Otherwise consumers cannot test the e2e

Issues

Notifies elastic/beats#30404

[mergify]

This pull request does not have a backport label. Could you fix it @v1v? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-v./d./d./d is the label to automatically backport to the 7./d branch. /d is the digit
  NOTE: backport-skip has been added to this pull request.

[mdelapenya]

Could we update the .backport file too?

[v1v]

I'll do it in a new PR

[elasticmachine]

💚 Flaky test report

Tests succeeded.

🤖 GitHub comments

To re-run your PR in the CI, just comment with:

• /test : Re-trigger the build.