fixes#18888
## Summary
`make run-android` was sometimes flaky because we used to send metro to background via `nohup` and then bring it back to foreground after we read metro logs.
Now we do not send metro to background. We first wait for a successful build.
we then install the app on the simulator. After this is done we give command to sleep until metro server has started, Once metro server has started we open the installed app.
In this workflow the command to open the installed app goes in background and metro stays in foreground.
The new workflow should now be less flaky.
## Review notes
`make run-clojure`
`make run-android` OR `make run-ios` should just work
#### Platforms
- Android
- iOS
Siddarth Kumar