init: disallow reindex-chainstate when pruning

Summary:

This fixes a bug where the node would be stuck in an
endless loop when combining these parameters.

Backport of core#24626.

Depends on D17388.

Test Plan:

./test/functional/test_runner.py feature_pruning

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D17389