[Chronik] Disallow combining -prune and -chronik
Summary: Chronik requires all the block data to be present, so we error when pruning is enabled.
Test Plan: ninja && ./test/functional/test_runner.py chronik_disallow_prune
Reviewers: Fabien, #bitcoin_abc, sdulfari
Reviewed By: #bitcoin_abc, sdulfari
Subscribers: sdulfari
Differential Revision: https://reviews.bitcoinabc.org/D13336