refactor: replace Boost shared_mutex with std shared_mutex in cuckoocache tests
refactor: replace Boost shared_mutex with std shared_mutex in sigcache
build: don't build or use Boost Thread
Co-authored-by: MarcoFalke falke.marco@gmail.com
Co-authored-by: sinetek pitwuu@gmail.com
This is a backport of core#21064
Depends on D13963