Remove dead ExceptionBreakpointSpec

[Yicong-Huang]

Task Summary

Two pieces of dead code remain from the old Scala tuple-level breakpoint mechanism in the Amber engine:

1. amber/src/test/scala/.../breakpoint/ExceptionBreakpointSpec.scala — all 7 test cases commented out since Enabling a few e2e test cases in Amber #941 (2020-12-21), over 5 years of dead code. Subsequent commits only renamed packages (apache migration, pekko switch).
2. amber/src/main/scala/.../common/amberexception/BreakpointException.scala — the sole class in its package, zero references anywhere in amber/ or common/.

These targeted the old tuple-level breakpoint mechanism (faulted/conditional/count breakpoints handled via ReportGlobalBreakpointTriggered / SkipTuple / ModifyTuple). The other production classes from this system (LocalBreakpoint, FaultedTuple, SkipTuple (the engine class, not SkipTupleRequest), ModifyTuple, ExceptionBreakpoint, ReportGlobalBreakpointTriggered) have already been removed.

This is unrelated to the modern Python UDF debugger (Udon), which is covered by frontend specs.

Proposed Action

Delete both files. Remove the now-empty breakpoint/ test directory and amberexception/ main package directory.

Priority

P3 – Low (cleanup)

Task Type

• Refactor / Cleanup
• Testing / QA