Revert "minor #60377 [HttpFoundation] Emit PHP warning when Response::sendHeaders() is called while output has already been sent (ivo95v)"

This reverts commit cf554e1be6338c1176832dd4cdf713d88d3144ad, reversing
changes made to 392d0c9c407d6b06a072600fe9dc2a779b231ce0.

Author: nicolas-grekas

Response.php

@@ -317,11 +317,6 @@ public function sendHeaders(?int $statusCode = null): static
     {
         // headers have already been sent by the developer
         if (headers_sent()) {
-            if (!\in_array(\PHP_SAPI, ['cli', 'phpdbg', 'embed'], true)) {
-                $statusCode ??= $this->statusCode;
-                header(\sprintf('HTTP/%s %s %s', $this->version, $statusCode, $this->statusText), true, $statusCode);
-            }
-
             return $this;
         }