Remove redundant default attributes from phpunit.xml (#5233)

phpunit.xml

@@ -1,15 +1,8 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:noNamespaceSchemaLocation="./vendor/phpunit/phpunit/phpunit.xsd"
-         backupGlobals="false"
-         backupStaticAttributes="false"
          bootstrap="vendor/autoload.php"
-         colors="true"
-         convertErrorsToExceptions="true"
-         convertNoticesToExceptions="true"
-         convertWarningsToExceptions="true"
-         processIsolation="false"
-         stopOnFailure="false">
+         colors="true">
     <testsuites>
         <testsuite name="Unit">
             <directory suffix="Test.php">./tests/Unit</directory>