Summary of the contribution

Update Zeek to 4.0.5 and librdkafka to 1.4.4. Updating librdkafka to the latest release failed; separating that effort for another time.

Breaking change

This removes support for Centos 8, which was already non-functional.

Leverage built-in tests.

[X] Confirm that any associated issues are indicated in the pull request title
[X] Rebase your PR against the latest commit within the target branch
[X] Include steps to verify and test the intended change
[X] Write or update unit tests and/or integration tests to verify your changes
[X] Run shellcheck against any new or updated shell scripts, indicating the reasoning behind any disabled checks
[X] Indicate whether or not this is a breaking change
[X] Ensure that any new dependencies are these dependencies licensed in a way that is compatible for inclusion under ASF 2.0