[test] truncate pledge block when cleaning up financial entities

Keep hunting down the test cleanup issue

tests/phpunit/CiviTest/CiviUnitTestCase.php

@@ -1778,6 +1778,7 @@ AND    ( TABLE_NAME LIKE 'civicrm_value_%' )
       'civicrm_participant',
       'civicrm_participant_payment',
       'civicrm_pledge',
+      'civicrm_pledge_block',
       'civicrm_pledge_payment',
       'civicrm_price_set_entity',
       'civicrm_price_field_value',