[chronik] Let the indexer access the node bridge

Summary:
So far the bridge was passed down everywhere it's needed. This diff allows for lots of code improvements and simplification, starting with the removal of the lambda that were a workaround for this missing bridge access.

It's not used in the indexer methods yet so the member is prefixed with an underscore, this will be removed in follow up diffs.

Depends on D18428.

Test Plan:

ninja all check check-functional check-chronik-crate

Reviewers: #bitcoin_abc, alitayin, tobias_ruck

Reviewed By: #bitcoin_abc, alitayin, tobias_ruck

Differential Revision: https://reviews.bitcoinabc.org/D18429