Use only Span{} constructor for byte-like types where possible
Summary:
This removes bloat that is not needed.
This concludes backport of core#27927
https://github.com/bitcoin/bitcoin/pull/27927/commits/fa38d862358b87219b12bf31236c52f28d9fc5d6
Depends on D19029
Test Plan: ninja all check-all
Reviewers: #bitcoin_abc, Fabien
Reviewed By: #bitcoin_abc, Fabien
Differential Revision: https://reviews.bitcoinabc.org/D19030