AC-1989: Fix subset of deprecated php usages

- Fixes for php code

Author: Rrego6

app/code/Magento/MediaStorage/App/Media.php

@@ -238,7 +238,8 @@ private function createLocalCopy(): void
      */
     private function checkMediaDirectoryChanged(): bool
     {
-        return rtrim($this->mediaDirectoryPath, '/') !== rtrim($this->directoryMedia->getAbsolutePath(), '/');
+        return rtrim($this->mediaDirectoryPath ?? '', '/')
+            !== rtrim($this->directoryMedia->getAbsolutePath() ?? '', '/');
     }
 
     /**

app/code/Magento/SalesRule/Model/Quote/Discount.php

@@ -296,7 +296,7 @@ public function fetch(Quote $quote, Total $total)
             $description = $total->getDiscountDescription();
             $result = [
                 'code' => $this->getCode(),
-                'title' => strlen( is_string($description) ? $description : '') ? __('Discount (%1)', $description) : __('Discount'),
+                'title' => strlen($description ?? '') ? __('Discount (%1)', $description) : __('Discount'),
                 'value' => $amount
             ];
         }