test: remove redundant MD5 regex loop in testSplitWithMd5Option

The loop verifying filenames match MD5 regex pattern is redundant because
the subsequent assertEquals($expectedHash, $basename) already verifies
that each filename equals the expected MD5 hash of the URL. Since md5()
always returns a 32-character hex string, the regex check adds no value.

Author: claude

tests/src/Functional/SplitCommandTest.php

@@ -109,13 +109,7 @@ public function testSplitWithMd5Option(): void
         $files = glob($this->tempDir.'/*.har');
         $this->assertCount(11, $files);
 
-        // Verify file names are MD5 hashes
-        foreach ($files as $file) {
-            $basename = basename($file, '.har');
-            $this->assertMatchesRegularExpression('/^[a-f0-9]{32}$/', $basename, 'Filename should be MD5 hash');
-        }
-
-        // Verify each file is valid HAR
+        // Verify each file is valid HAR and filename matches MD5 of URL
         $serializer = new Serializer();
         foreach ($files as $file) {
             $contents = file_get_contents($file);