Merge #16538: test: Add missing sync_blocks to feature_pruning
Summary: PR16538 backport. Replaces D5162 .
Test Plan:
ninja all && ./test/functional/test_runner.py feature_pruning
Reviewers: #bitcoin_abc, deadalnix
Reviewed By: #bitcoin_abc, deadalnix
Subscribers: deadalnix
Differential Revision: https://reviews.bitcoinabc.org/D5168