move relevant information to dependency management section

[janjwerner-confluent]

PoC of POM file cleanup: move of dependency management to top level pom, cleanup of versions / sections of dependency entries not relevant in given context.

[confluent-cla-assistant[bot]]

:tada: All Contributor License Agreements have been signed. Ready to merge.
_{Please push an empty commit if you would like to re-run the checks to verify CLA status for all contributors.}