Fix --view-protocol failures

mysql-test/include/empty_string_literal.inc

 SET SESSION character_set_connection=latin2;
 SET SESSION character_set_client=cp1250;
 
+--disable_service_connection
+
 --echo #
 --echo # Test litteral
 --echo #
@@ -129,3 +131,5 @@ EXPLAIN EXTENDED SELECT '';
 EXPLAIN EXTENDED SELECT _latin1'';
 EXPLAIN EXTENDED SELECT N'';
 EXPLAIN EXTENDED SELECT '' '';
+
+--enable_service_connection

mysql-test/main/mdl.test

@@ -84,6 +84,7 @@ DROP TABLE t1,t3;
 --echo #
 --echo # MDEV-28820 MyISAM wrong server status flags
 --echo #
+--disable_service_connection
 # MyISAM alone doesn't start a transaction or takes transactional MDL
 create table t1 (a int);
 set autocommit=0;
@@ -119,6 +120,7 @@ disconnect foo;
 connection default;
 set autocommit=default;
 drop table t2;
+--enable_service_connection
 
 --echo #
 --echo # End of 10.4 tests

mysql-test/main/sql_mode.test

@@ -575,7 +575,9 @@ DELIMITER ;$$
 
 SET sql_mode='ORACLE,EMPTY_STRING_IS_NULL';
 SELECT @@sql_mode;
+--disable_service_connection
 SELECT '' AS empty;
+--enable_service_connection
 SET sql_mode='';
 SELECT @@sql_mode;
 SET sql_mode=DEFAULT;