clearToken
Removes the shared Nightbreak token from disk and this shaded classloader.
The configuration file itself is deleted so a token cannot remain in comments, backups, or an empty placeholder value. Other shaded copies observe the missing file from ensureFresh on their next access, which makes logout propagate without a server restart.
Return
true when no token remains, otherwise false
Parameters
plugin
plugin whose data-folder parent identifies the shared MagmaCore configuration directory