Error "USER-STORE [ERROR] Server error: listen tcp :8084: bind: address already in use" when running in Azure

When PrivX is deployed in Azure, the User Store microservice may fail to start with an error:

USER-STORE [ERROR] Server error: listen tcp :8084: bind: address already in use

This indicates that a process has reserved port 8084 on the system. In Microsoft Azure, this may be due to Microsoft OMS agent occupying the port.

https://github.com/microsoft/OMS-Agent-for-Linux/blob/master/installer/scripts/npm_startup.sh

To fix this, either move OMS Agent to a different port, uninstall it or configure the PrivX User Store microservice to use a different port.

To change the User-Store port, specify listen_port in the User-Store configuration at /opt/privx/etc/user-store.toml (replace 8888 with the number of a free port):
```
listen_port = 8888 # use a free port
```

In /etc/nginx/privx/privx-https-location.conf, set the User Store's proxy_pass to the matching port number (replace 8888 with the port number you used in the previous step):

location /local-user-store/api/v1/ {
        if ($request_uri !~* ^/local-user-store/api/v1/) {
                return 404;
        }
        proxy_pass      https://127.0.0.1:8888;
        include         privx/privx-proxy-headers.conf;
}

Restart PrivX and Nginx to apply your changes:
```
systemctl restart privx nginx
```