2442 remove pbas

[cakekoa]

What does this PR do?

Fixes #2442.

Removes PBA from the backend. Requires the agents to be rebuilt in order to test.

PR Checklist

• Have you added an explanation of what your changes do and why you'd like to include them?
• Is the TravisCI build passing?
• Was the CHANGELOG.md updated to reflect the changes?
• Was the documentation framework updated to reflect the changes?
• Have you checked that you haven't introduced any duplicate code?

Testing Checklist

• Added relevant unit tests?
• Have you successfully tested your changes locally? Elaborate:

  Tested by running in the zoo environment. Did not see any errors in the island log.

• If applicable, add screenshots or log transcripts of the feature working