Use @param mixed instead of native mixed type for PHP 7.4 compat, remove comments

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

Author: phpstan-bot

tests/PHPStan/Analyser/nsrt/bug-14469.php

@@ -18,10 +18,7 @@ function t(array $R, bool $var1, object $user): void {
 	}
 }
 
-/**
- * Variable equivalent: pre-defined variable stays mixed inside if ($aa)
- * @param mixed $input
- */
+/** @param mixed $input */
 function variableEquivalent($input, bool $var1, object $user): void {
 	$aa = null;
 	$bb = $input;

tests/PHPStan/Rules/Comparison/data/bug-14469.php

@@ -72,9 +72,7 @@ function multipleElseif(array $R, bool $var1, bool $var2, object $user): void {
     }
 }
 
-/**
- * @param mixed $input
- */
+/** @param mixed $input */
 function variableEquivalent(bool $var1, object $user, $input): void {
 	$aa = null;
 	$bb = $input;