MC-17218: php bin/magento catalog:image:resize error if image is missing

- Fixed unit test;

Author: Aliaksei Yakimovich2

app/code/Magento/MediaStorage/Test/Unit/Service/ImageResizeTest.php

@@ -248,7 +248,7 @@ function () {
         $this->mediaDirectoryMock->expects($this->any())
             ->method('isFile')
             ->with($this->testfilepath)
-            ->will($this->returnValue(false));
+            ->will($this->returnValue(true));
 
         $this->databaseMock->expects($this->once())
             ->method('saveFileToFilesystem')