Fix the response as expected by the test.

[adam-vessey]

Islandora\Crayfish\Commons\Tests\ApixMiddlewareTest::testReturns400IfNoApixLdpResourceHeader() expects an HTTP 400 to be emitted; however, it was not being done.

What does this Pull Request do?

Restores behaviour being tested that was changed in the move to Symfony bundles

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