[PhpUnitBridge] Search for other SYMFONY_* env vars

[javiereguiluz]

See symfony/symfony#26800 and symfony/symfony#26811

Hi @lyrixx! Your original pull request at symfony/symfony#26811 didn't contain any description, so it's hard for us to document it. Could you please tell us which changes or improvements does this PR introduce for end-users apps? Thank you!

[lyrixx]

Hello.

Actually, when one install the phpunit bridge and if she/he wants to use phrophecy also, she/he needs to set the SYMFONY_PHPUNIT_REMOVE env var to symfony/yaml. And this, each* time she/he runs the Test Suite. And to me it's really annoying.

With my PR, we could put this env var in the phpunit.xml(.dist).

ref https://symfony.com/doc/current/components/phpunit_bridge.html#modified-phpunit-script

[javiereguiluz]

Fixed by #9643.