revert(youtube): drop the unverified chunked-upload guard

YouTube uploads through the Google API client's resumable handler, not our
HTTP client, so the leak couldn't be reproduced for it and the nextChunk loop
can't be exercised by a test without making the Google client injectable.
Keeping this PR to changes that are both reproduced and covered by a test
(X and LinkedIn); YouTube is tracked separately.

app/Services/Social/YouTubePublisher.php

@@ -167,9 +167,6 @@ private function publishShort(PostPlatform $postPlatform, $media, SocialAccount
             while (! $uploadStatus && ! feof($handle)) {
                 $chunk = fread($handle, self::CHUNK_SIZE);
                 $uploadStatus = $mediaUpload->nextChunk($chunk);
-
-                unset($chunk);
-                $this->freeChunkMemory();
             }
 
             fclose($handle);