Remove bar() test case from bug-4090 regression test

The bar() function tested count narrowing via an intermediate variable,
which is a pre-existing limitation unrelated to this PR. The assertion
documented incorrect behavior (string|false instead of string).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: phpstan-bot

tests/PHPStan/Analyser/nsrt/bug-4090.php

@@ -17,19 +17,6 @@ function foo(array $a): void
 }
 
 
-/** @param string[] $a */
-function bar(array $a): void
-{
-	$count = count($a);
-	if ($count > 1) {
-		echo implode(',', $a);
-	} elseif ($count === 1) {
-		assertType('string|false', current($a));
-		echo trim((string) current($a));
-	}
-}
-
-
 /** @param string[] $a */
 function qux(array $a): void
 {