Replace bare except clauses in multicore_utils with specific exceptions

[Vaishnav88sk]

Problem

multicore_utils.py contains two bare except: clauses that catch all exceptions including SystemExit and KeyboardInterrupt. This is a Python anti-pattern that can mask real problems and interfere with process management in forked child processes.

Expected Behavior

• Import fallback should only catch ImportError
• Child process error handler should catch Exception but not SystemExit/KeyboardInterrupt