Never use aggregation in maintenance mode.

When we are in ANY maintenance mode, we do not want to allow aggregation.

When the database is down and the site is in error maintenance mode, the error pages would be attempting to do aggregation without having any way to update the state, causing additional load. The fallback maintenance page does not have any business attempting to aggregate anyway.

This check for != update mode had originally been intended in #199946: Stale css+js files on upgrade → to prevent both miscaching and exposing the drupal version, but it should have been taken out when the logic was changed to use an incrementing number.

You can see the original code that led to this in #199946-22: Stale css+js files on upgrade → .