tests: enable MariaDB/MySQL strict mode

Pass sql_mode=TRADITIONAL to the SQL connection which would raise an
error instead of warning, for example when a field is truncated.

This change will most probably cause some extensions test to start
magically failling.

Bug: T119371
Change-Id: I2051952090e48876f629690981e25603eff79f67

includes/DevelopmentSettings.php

@@ -36,6 +36,9 @@ $wgShowExceptionDetails = true;
 $wgShowHostnames = true;
 $wgDebugRawPage = true; // T49960
 
+// Enable MariaDB/MySQL strict mode
+$wgSQLMode = 'TRADITIONAL';
+
 // Enable log files
 $logDir = getenv( 'MW_LOG_DIR' );
 if ( $logDir ) {