system: Rename "symmetric" to "simultaneous" multithreading
system: Rename "symmetric" to "simultaneous" multithreading

Closes #11547
cockpituous/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,deryni/cockpit,cockpit-project/cockpit,deryni/cockpit,moraleslazaro/cockpit,garrett/cockpit,mvollmer/cockpit,cockpit-project/cockpit,mvollmer/cockpit,deryni/cockpit,cockpituous/cockpit,mvollmer/cockpit,deryni/cockpit,moraleslazaro/cockpit,deryni/cockpit,cockpit-project/cockpit,garrett/cockpit,mvollmer/cockpit,cockpit-project/cockpit,martinpitt/cockpit,mvollmer/cockpit,cockpituous/cockpit,deryni/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,martinpitt/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,garrett/cockpit,garrett/cockpit,deryni/cockpit,moraleslazaro/cockpit,cockpit-project/cockpit,martinpitt/cockpit,martinpitt/cockpit,martinpitt/cockpit,garrett/cockpit,cockpituous/cockpit