[chronik] get consensus params via chainman

Summary: The ChainstateManager has access to the config, so no need to pass it to ChronikBridge when it has already a NodeContext. This removes one GetConfig() call and is a step towards unglobalizing the Config.

Test Plan:

cmake .. -GNinja -DBUILD_BITCOIN_CHRONIK=ON
ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D16116