3261236: Use explicit SQL modes instead of ANSI and TRADITIONAL.

Closes #3261236 by explicitly listing all of the SQL modes instead of using the combined ANSI and TRADITIONAL modes.

The explicitly listed modes are based on the mysql definitions of ANSI and TRADITIONAL. There may be some further work required to determine whether they or some combination of the others used by mariadb are preferred.

core/modules/mysql/src/Driver/Database/mysql/Connection.php

@@ -222,7 +222,10 @@ public static function open(array &$connection_options = []) {
     ];
 
     $connection_options['init_commands'] += [
-      'sql_mode' => "SET sql_mode = 'ANSI,TRADITIONAL'",
+      'sql_mode' => "SET sql_mode = 'REAL_AS_FLOAT,PIPES_AS_CONCAT,ANSI_QUOTES,"
+        . "IGNORE_SPACE,ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,STRICT_ALL_TABLES,"
+        . "NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,"
+        . "NO_ENGINE_SUBSTITUTION'",
     ];
 
     // Execute initial commands.

[daffie]

Could we add a comment with that we used sql_mode "ANSI,TRADITIONAL", only that we changed it because of differences between MySQL and MariaDB.