Refactor #getInvitationBreadcrumbTrail macro and remove the old breadcrumb generation

XWIKI-13065 removed the custom breadcrumb and relies on the default one.

The #getInvitationBreadcrumbTrail macro should be rewritten in order not to duplicate code and remove the not-used code remaining.

I've created this issue in order not to forget about it and since the refactoring should be done correctly.