Switch whisper and mailserver nodes to new config

[adambabik]

After status-go got refactored and JSON config files started to be used, we needed to fix our infrastructure code.

This PR changes Whisper and Mail Server configuration.

Please do not merge before the correctness of this PR is confirmed on "eth.staging".

Todo

• [x] deploy on "eth.test"
• [ ] deploy on "eth.staging" and test with Status Mobile and Status Desktop