When all matching printers were busy and a job was queued with ASAP
timing, the scheduler immediately fired a "Job Waiting for Filament"
notification even though the job was just waiting for a printer to
finish — no user action required.
Added _is_busy_only() check to skip the waiting notification when the
only reason is "Busy". Notifications still fire for actionable reasons
(missing filament, offline, wrong color). Also renamed the default
notification template title to "Queue Job Waiting" and updated
descriptions across all 7 locales.