Partly revert wrong expectations (#5589)

Author: staabm

tests/PHPStan/Rules/Arrays/OffsetAccessAssignmentRuleTest.php

@@ -222,15 +222,4 @@ public function testAppendToArrayWithPhpIntMaxKey(): void
 		]);
 	}
 
-	public function testBug9004(): void
-	{
-		$this->checkUnionTypes = true;
-		$this->analyse([__DIR__ . '/../../Analyser/nsrt/bug-9004.php'], [
-			[
-				'Cannot assign new offset to list<int>|string.',
-				14,
-			],
-		]);
-	}
-
 }