Concurrency Properties added to config

[joneubank]

Through the refactoring of the release process, several places have added code that is running DB and HTTP requests in parallel and limiting the concurrency with hardcoded numbers.

We want to move this into the config with sensible defaults and make them editable through environmental config if changes are ever needed. Likely these will never need to be edited but it would be good to be able to change them for a given environment based on performance issues without requiring code changes.