Revert "Adding Delete Custom Variable Test"

This reverts commit c02e4ac.

Author: eduard13

app/code/Magento/Variable/Test/Mftf/Data/VariableData.xml

@@ -17,7 +17,4 @@
         <data key="html"> Sample Variable </data>
         <data key="plain">variable-plain-</data>
     </entity>
-    <entity name="customVariableV2" type="system_variable" extends="customVariable">
-        <data key="code" unique="suffix">variable-code-</data>
-    </entity>
 </entities>