CBlockLocator: performance-move-const-arg Clang tidy fixups

Summary:
Backport of core#25963.

Fix explicit move for RVO and make the CBlockLocator constructor move the hashes.

Test Plan:

ninja all check-all

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D16286