Eg when Matomo is not installed, it would still dispatch the request in https://github.com/matomo-org/matomo/blob/3.8.1-b1/plugins/Installation/Installation.php#L111 even when
PIWIK_ENABLE_DISPATCH is disabled.
Will set it to WIP for now as I'm not sure if we want to have this actually merged or not.
Not sure we can easily add a test for this? Basically the idea is to throw the exception when dispatch is disabled.