RUBY-2820 use session registry from mrss (#5173)

* RUBY-2820 use mrss session_registry

* RUBY-2820 include old session registry

* RUBY-2820 update version check

* remove unnecessary spacing

Author: neilshweky

spec/lite_spec_helper.rb

@@ -18,7 +18,14 @@
 
 require 'support/spec_config'
 require 'mrss/lite_constraints'
-require "support/session_registry"
+
+if Gem::Version.new(Mongo::VERSION) < Gem::Version.new('2.18.0.alpha')
+  require "mrss/session_registry_legacy"
+else
+  require "mrss/session_registry"
+end
+
+Mrss.patch_mongo_for_session_registry
 
 unless SpecConfig.instance.ci?
   begin

spec/mongoid/query_cache_spec.rb

@@ -17,11 +17,11 @@
     # occur only within the scope of these tests.
     #
     # Other session leaks will be detected and addressed as part of RUBY-2391.
-    SessionRegistry.instance.clear_registry
+    Mrss::SessionRegistry.instance.clear_registry
   end
 
   after do
-    SessionRegistry.instance.verify_sessions_ended!
+    Mrss::SessionRegistry.instance.verify_sessions_ended!
   end
 
   let(:reset_legacy_qc_warning) do