Grafana HTTP Proxy configuration

Hi there,
I am trying to use a proxy connection to connect to things for alerts using Microsoft Teams webhook. I have added the HTTP and HTTPS_PROXY into /etc/sysconfig/grafana-server and its worked.

However, I facing the issues whereby the password is show in plaintext in the configuration file. Hence, I would to check is there any ways to hide or prevent the password be shown in plaintext (which is minimum requirement)? On the side note, the server have no network access to outside and no installation of external linux library is allowed as well.

My current input is show as below,