ActiveContext Find partition by serializing collection

ee/app/models/ai/active_context/collection.rb

ee/spec/models/ai/active_context/collection_spec.rb

...lab-active-context/lib/active_context/collection_cache.rb

...-active-context/lib/active_context/concerns/collection.rb

...itlab-active-context/lib/active_context/concerns/queue.rb

gems/gitlab-active-context/lib/active_context/config.rb

...context/lib/active_context/databases/concerns/executor.rb

gems/gitlab-active-context/lib/active_context/hash.rb

gems/gitlab-active-context/lib/active_context/reference.rb

gems/gitlab-active-context/lib/active_context/shard.rb

...ve-context/spec/lib/active_context/concerns/queue_spec.rb

...lab-active-context/spec/lib/active_context/config_spec.rb

...-active-context/spec/lib/active_context/reference_spec.rb

...ab-active-context/spec/lib/active_context/tracker_spec.rb