Remove unused SCHEDULER_TIME_SLOT_EXPIRED_PAUSE pause type and dead handler

[Yicong-Huang]

Task Summary

SchedulerTimeSlotExpiredPause (Scala) and PauseType.SCHEDULER_TIME_SLOT_EXPIRED_PAUSE (Python) are no longer referenced anywhere in the codebase. The Python MainLoop._scheduler_time_slot_event handler that uses this pause type is also never called. Remove this dead code.

Files affected:

• amber/src/main/scala/org/apache/texera/amber/engine/architecture/worker/PauseType.scala — drop SchedulerTimeSlotExpiredPause.
• amber/src/main/python/core/architecture/managers/pause_manager.py — drop SCHEDULER_TIME_SLOT_EXPIRED_PAUSE enum entry.
• amber/src/main/python/core/runnables/main_loop.py — drop the unused _scheduler_time_slot_event method.

Priority

P3 – Low

Task Type

• Refactor / Cleanup