Update- To clarify this further i also reached out to App Service Engineering team and here is what they said.
The App Service Editor feature is a preview product and the run button has been removed . 
in the recent platform updates. These updates will take a few weeks to roll out across all the stamps/regions. That is why you may still see the run button in some of the apps.
If you want to make changes to your application code, you can access the kudu service using Advanced tools under Development Tools.
Please let me know if you have any further questions on this issue.