Add some missing configs to the config setup

[pgimalac]

What does this PR do?

Add some missing configs in the config setup, so that they are properly declared (and "known"):

• apm_config.max_catalog_entries
• dogstatsd_workers_count

Motivation

All configs should be declared, so that using IsKnown returns true for a "real" config.

Additional Notes

Possible Drawbacks / Trade-offs

Describe how to test/QA your changes