Always respond to `set_server_option` since mysql2 0.5.0

https://github.com/brianmario/mysql2/pull/943
https://github.com/rails/rails/pull/37191

activerecord/lib/active_record/connection_adapters/mysql/database_statements.rb

@@ -97,39 +97,27 @@ def last_inserted_id(result)
             @connection.last_id
           end
 
-          def supports_set_server_option?
-            @connection.respond_to?(:set_server_option)
-          end
+          def multi_statements_enabled?
+            flags = @config[:flags]
 
-          def multi_statements_enabled?(flags)
             if flags.is_a?(Array)
               flags.include?("MULTI_STATEMENTS")
             else
-              (flags & Mysql2::Client::MULTI_STATEMENTS) != 0
+              flags.anybits?(Mysql2::Client::MULTI_STATEMENTS)
             end
           end
 
           def with_multi_statements
-            previous_flags = @config[:flags]
+            multi_statements_was = multi_statements_enabled?
 
-            unless multi_statements_enabled?(previous_flags)
-              if supports_set_server_option?
+            unless multi_statements_was
               @connection.set_server_option(Mysql2::Client::OPTION_MULTI_STATEMENTS_ON)
-              else
-                @config[:flags] = Mysql2::Client::MULTI_STATEMENTS
-                reconnect!
-              end
             end
 
             yield
           ensure
-            unless multi_statements_enabled?(previous_flags)
-              if supports_set_server_option?
+            unless multi_statements_was
               @connection.set_server_option(Mysql2::Client::OPTION_MULTI_STATEMENTS_OFF)
-              else
-                @config[:flags] = previous_flags
-                reconnect!
-              end
             end
           end
 

activerecord/test/cases/fixtures_test.rb

@@ -147,7 +147,6 @@ def test_bulk_insert_with_multi_statements_enabled
           ]
         }
 
-        ActiveRecord::Base.connection.stub(:supports_set_server_option?, false) do
         assert_nothing_raised do
           conn = ActiveRecord::Base.connection
           conn.execute("SELECT 1; SELECT 2;")
@@ -170,7 +169,6 @@ def test_bulk_insert_with_multi_statements_enabled
         end
       end
     end
-    end
 
     def test_bulk_insert_with_multi_statements_disabled
       run_without_connection do |orig_connection|
@@ -184,7 +182,6 @@ def test_bulk_insert_with_multi_statements_disabled
           ]
         }
 
-        ActiveRecord::Base.connection.stub(:supports_set_server_option?, false) do
         assert_raises(ActiveRecord::StatementInvalid) do
           conn = ActiveRecord::Base.connection
           conn.execute("SELECT 1; SELECT 2;")
@@ -203,7 +200,6 @@ def test_bulk_insert_with_multi_statements_disabled
         end
       end
     end
-    end
 
     def test_insert_fixtures_set_raises_an_error_when_max_allowed_packet_is_smaller_than_fixtures_set_size
       conn = ActiveRecord::Base.connection