MAGETWO-98522: Adding out of stock items to comparison shows success message but fails

- Fix functional test

Author: YuliyaLabudova

app/code/Magento/Catalog/Test/Mftf/Test/AddOutOfStockProductToCompareListTest.xml

@@ -47,6 +47,7 @@
 
         <!--Clear cache-->
         <actionGroup ref="ClearCacheActionGroup" stepKey="clearCache" />
+        <magentoCLI command="indexer:reindex" stepKey="reindex"/>
 
         <!--Open product page-->
         <amOnPage url="$$product.name$$.html" stepKey="goToSimpleProductPage2"/>