fix(s3): fix handling verify_bucket_exists parameter

If 'verify_bucket_exists' is set to false in the config.php s3 configuration, it's supposed to avoid
verifying that the bucket exists. However empty(falsy) will  always return true, so this condition
would not work.

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/private/Files/ObjectStore/S3ConnectionTrait.php

@@ -92,7 +92,7 @@ protected function parseParams($params) {
 		if (!isset($params['port']) || $params['port'] === '') {
 			$params['port'] = (isset($params['use_ssl']) && $params['use_ssl'] === false) ? 80 : 443;
 		}
-		$params['verify_bucket_exists'] = empty($params['verify_bucket_exists']) ? true : $params['verify_bucket_exists'];
+		$params['verify_bucket_exists'] = $params['verify_bucket_exists'] ?? true;
 		$this->params = $params;
 	}