minor #11344 remove defaults from PHPUnit configuration (craue)

This PR was merged into the 2.3 branch.

Discussion
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remove defaults from PHPUnit configuration

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | --
| License       | MIT
| Doc PR        | --

Follow-up to #11329.

Commits
-------

afc4930 removed defaults from PHPUnit configuration

Author: fabpot

phpunit.xml.dist

@@ -3,13 +3,7 @@
 <phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:noNamespaceSchemaLocation="http://schema.phpunit.de/4.1/phpunit.xsd"
          backupGlobals="false"
-         backupStaticAttributes="false"
          colors="true"
-         convertErrorsToExceptions="true"
-         convertNoticesToExceptions="true"
-         convertWarningsToExceptions="true"
-         processIsolation="false"
-         stopOnFailure="false"
          bootstrap="vendor/autoload.php"
 >
     <testsuites>