Fix run-tests.php differ calculateCommonSubsequence for EXPECTF

calculateCommonSubsequence should not contain regexes.

Fixes GH-13083
Closes GH-13084

run-tests.php

@@ -4138,7 +4138,7 @@ final class Differ
         if ($cFrom === 1) {
             foreach ($to as $toV) {
                 if (($this->isEqual)($from[0], $toV)) {
-                    return [$from[0]];
+                    return [$toV];
                 }
             }