The "You are running an outdated Graylog version" is stuck at the version of graylog when this system notification first appears

Graylog periodically checks to see if a newer version is available. If a newer version is available, graylog displays a system notification such as:

However, if one does not clear/dismiss this system notification, you will never receive another system notification of this type.

## Expected Behavior

If a newer version of graylog is available, replace the existing system notification.

## Current Behavior

System notification is frozen in time, never updates, may incorrectly say the "latest version is XYZ" when that could an older version.

## Possible Solution

## Steps to Reproduce (for bugs)

1. Install a graylog version older than the latest
2. Wait for the periodical to run (I believe this occurs 5 minutes after a graylog node "boots" and once every 30 min)
3. Wait for a newer version of graylog to be released (or hijack the update URL somehow, https://versioncheck.graylog.com/check )

Please let me know if there are any questions. This is very minor but this was brought up by @Joel-Duffield-Graylog when he noticed a cluster saying the latest version was a much older version than the latest.