Enhance quota exceeded logging for admins

* Adds owner of target folder (i.e. when shared)
* Clarifies user quota (vs disk space) issue

Addresses backend portion of #37519

Signed-off-by: Josh Richards <josh.t.richards@gmail.com>

apps/dav/lib/Connector/Sabre/QuotaPlugin.php

@@ -202,12 +202,13 @@ public function checkQuota($path, $length = null) {
  // use target file name for free space check in case of shared files
  $path = rtrim($parentPath, '/') . '/' . $info['name'];
  }
+ $targetOwner = $this->view->getOwner($path);
  $freeSpace = $this->getFreeSpace($path);
  if ($freeSpace >= 0 && $length > $freeSpace) {
  if (isset($chunkHandler)) {
  $chunkHandler->cleanup();
  }
- throw new InsufficientStorage("Insufficient space in $path, $length required, $freeSpace available");
+ throw new InsufficientStorage("Quota exceeded in $path (owner: $targetOwner), $length required, $freeSpace available");
  }
  }
  return true;