clang-tidy: Fix modernize-use-default-member-init in CScriptCheck

Summary:
This concludes backport of core#26749
https://github.com/bitcoin/bitcoin/pull/26749/commits/a87fb6bee5a7fb0879b3adea9a29997f1331acb0

Depends on D16147

Test Plan: ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D16148