message: Fix typo in work-stealing config params reading
diff: #include "caf/scheduler/abstract_coordinator.hpp"
  #define CONFIG(str_name, var_name) \
  - get_or(p->config(), "work-stealing." str_name, \
  + get_or(p->config(), "caf.work-stealing." str_name, \
  defaults::work_stealing::var_name)
  namespace caf::policy {
  