Improvements

• #6044: Do not deepcopy slots when instantiating trackers. This leads to a significant
  speedup when training on domains with a large number of slots.

• #6226: Added more debugging logs to the lock-stores to simplify debugging in case of
  connection problems.

  Added a new parameter socket_timeout to the RedisLockStore. If Redis doesn't
  answer within socket_timeout seconds to requests from Rasa Open Source, an error
  is raised. This avoids seemingly infinitely blocking connections and exposes connection
  problems early.

Bugfixes

• #5182: Fixed a bug where domain fields such as store_entities_as_slots were overridden
  with defaults and therefore ignored.
• #6191: If two entities are separated by a comma (or any other symbol), extract them as two separate entities.
• #6340: If two entities are separated by a single space and uses BILOU tagging,
  extract them as two separate entities based on their BILOU tags.