OEL-309: Remove phpunit cache.

phpunit.xml.dist

 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit bootstrap="${drupal.root}/core/tests/bootstrap.php" backupGlobals="true" colors="true" >
+<phpunit bootstrap="${drupal.root}/core/tests/bootstrap.php" backupGlobals="true" colors="true" cacheResult="false">
   <php>
     <ini name="error_reporting" value="32767"/>
     <ini name="memory_limit" value="-1"/>