Remove non-working test for now

Author: ondrejmirtes

tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php

@@ -926,12 +926,4 @@ public function testBug3747(): void
 		$this->analyse([__DIR__ . '/data/bug-3747.php'], []);
 	}
 
-	public function testBug8372(): void
-	{
-		$this->checkExplicitMixed = true;
-		$this->checkImplicitMixed = true;
-
-		$this->analyse([__DIR__ . '/data/bug-8372.php'], []);
-	}
-
 }