Refactor PCBPlace.py without changing functionality

[cpldcpu]

Refactor the 30_PLACE/PCBPlace.py file to improve readability and maintainability.

• Constants: Add constants for default values such as DEFAULT_PITCH_X, DEFAULT_PITCH_Y, DEFAULT_ARRAY_X_WIDTH, etc.
• Code Cleanup: Remove commented-out code and unnecessary comments.
• Formatting: Fix formatting issues such as extra spaces and inconsistent indentation.

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