"http_publish_uri" is not considering "http_enable_tls = true"

## Expected Behavior
After setting "http_enable_tls = true" an restarting the service the service should ow be accessable by https://...

## Current Behavior
- after "http_enable_tls = true" + restart service I get only a blank page. The title was set in the webbrowser window.
- after setting: "http_publish_uri = https://$http_bind_address/" i see a information page:
> Server currently unavailable
> We are experiencing problems connecting to the Graylog server running on https:%2Fapi%2F. Please verify that the server is healthy and working correctly.
- after setting: "http_publish_uri = https://somehostname:9000/" I can login again.

## Possible Solution
I guess, that the default "http_publish_uri" und "api_uri" are not correctly considering "http_enable_tls = true".

## Steps to Reproduce (for bugs)
1. install a fresh graylog instance with default parameter
2. set http_enable_tls = true, http_tls_cert_file and http_tls_key_file
3. restart the service
4. try the browse the expected publish uri

## Context
I' m trying to enable TLS for all services on my host

## Your Environment

* Graylog Version: 3.2.4+a407287
* Elasticsearch Version: 6.8.8
* MongoDB Version: v4.2.6
* Operating System: Ubuntu 18.04.4 LTS
* Browser version: Chrome 81.0.4044.92, IE 11.778