[FIX] [APPS] Warn message while installing app in air-gapped environment

[lucassartor]

Proposed changes (including videos or screenshots)

Change error message to a warn message when uploading a .zip file app into a air-gapped environment.

The error message was giving the impression for the user that the app wasn't properly being installed , which it wasn't the case:

A more detailed warn message can fix that impression for the user:

Issue(s)

Fixes Task

Steps to test or reproduce

1. Go to Admin > Logs and change the log level to at least 1 (warn messages are level 1)
2. Cut the internet connection from a Rocket Chat server
3. Upload a .zip app file and installed it
4. The message will appear in the console

Further comments

[d-gubert]

Nicely done!