Removing purge key from app settings and uploading to server does not disable purging

[sugat009]

Describe the bug
This issue is related to #642. This is mostly related to the upload part. After removing the purge key manually from app_settings.json and uploading it to the server. It doesn't get updated in the settings in the database.

To Reproduce
Steps to reproduce the behavior:

1. Create a purge.js file and add your purge logic
2. Run the command cht compile-app-settings upload-app-settings
3. Purging should be enabled
4. Manually remove the purge key from the app_settings.json file
5. Run the command cht upload-app-settings
6. Check if purging is disabled

Expected behavior
Purging should be disabled if the purge key is removed from the app_settings.json file and uploaded to the server.

Logs
If applicable, include the cht-conf output, server logs, and/or browser logs.

Screenshots
If applicable, add screenshots to help explain your problem.

Environment

• Instance: Local
• Client platform: Linux
• cht-conf version: 4.1.1
• cht-core version: 4.13

Additional context
A workaround as described in #642 is to make the purging.js file blank and then, compile and upload the settings works but it creates a key in the settings in the database with an empty object which is probably not ideal.