Auth: Init global user for "blocked authentication" state (fix for `$DIC->user()->getId() === 0`)

[mjansenDatabay]

See: https://mantis.ilias.de/view.php?id=41601

If approved, this MUST be picked to all maintained branches.

This will init/set the global user object in case \ilInitialisation::blockedAuthentication returns true, so the user id of a non-logged-in user will be 13 and not 0 for these cases.