Handle authorization errors in Kafka output

[belimawr]

Proposed commit message

When there is an authorisation error in the Kafka output, the events are dropped and an error message is logged.

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
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

## Disruptive User Impact
## Author's Checklist

How to test this PR locally

Run the tests added by this PR:

mage buildSystemTestBinary
go test -tags integration -run=TestAuthorisationErrors -v ./tests/integration

If you want to run any Beat yourself, you can modify the test so it only starts the mock and waits, then configure a Beat to connect to it.

Related issues

• Closes Kafka output causes high CPU usage when ACL is missconfigured #42343

## Use cases
## Screenshots
## Logs

[mergify]

This pull request is now in conflicts. Could you fix it? 🙏
To fixup this pull request, you can check out it locally. See documentation: https://help.github.com/articles/checking-out-pull-requests-locally/

git fetch upstream
git checkout -b 42343-kafka-handle-auth-error upstream/42343-kafka-handle-auth-error
git merge upstream/main
git push upstream 42343-kafka-handle-auth-error

[mergify]

This pull request does not have a backport label.
If this is a bug or security fix, could you label this PR @belimawr? 🙏.
For such, you'll need to label your PR with:

• The upcoming major version of the Elastic Stack
• The upcoming minor version of the Elastic Stack (if you're not pushing a breaking change)

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

[mergify]

backport-8.x has been added to help with the transition to the new branch 8.x.
If you don't need it please use backport-skip label and remove the backport-8.x label.

[elasticmachine]

Pinging @elastic/elastic-agent-data-plane (Team:Elastic-Agent-Data-Plane)