hotline #17191 reset bluga_key to fix test failures

tests/library/ZendAfi/View/Helper/WebThumbnailTest.php

@@ -134,6 +134,8 @@ $this->google_thumbnail_path = USERFILESPATH.'/web_thumbnails/www_google_com.jpg
 
 	/** @test */
 	public function thumbnailerCannotFetchImageAndBlugaDisabledReturnsEmptyUrl() {
+		Class_AdminVar::newInstanceWithId('BLUGA_API_KEY', ['valeur' => '']);
+
 		$this->_file_writer
 			->whenCalled('fileExists')
 			->with($this->google_thumbnail_path)