Addressing robustness of Drain.py

[Aaryaveerkrishna23]

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This PR enhances the log parsing functionality by addressing string handling and error resilience. Key improvements include:

• String Handling: Ensured all inputs and intermediates are explicitly converted to strings, particularly before regex operations, to prevent type-related errors.

• Robust Exception Handling: Implemented comprehensive exception handling across parsing functions to gracefully capture and report errors without interrupting the processing flow.

• Malformed Line Processing: Added logic to effectively parse and standardize malformed or incomplete log entries, improving reliability across diverse log data formats.

• Regex Validation: Reviewed and validated regex patterns to ensure correct formation, preventing syntax-related issues.

• Enhanced Debugging: Introduced detailed print statements around error-prone areas to facilitate easy identification and debugging of issues.

These changes collectively improve the parser's robustness, ensuring it can handle various inconsistencies and edge cases in log files efficiently.

[zhujiem]

Thanks for your PR to enhance robustness of Drain. But we hope to keep it to be simple and concise so that it can be run on the given environment.