Refactor: Simplify XML replacement logic and remove redundant indentation handling

[pyob-bot]

Summary of Changes

• Refactored the search-and-replace logic in ApplyXMLMixin to use raw search_lines instead of pre-stripped versions, ensuring more accurate matching.
• Removed the _fix_replace_indentation method call during the replacement process.
• Simplified the new_code_lines construction by directly injecting replace_lines instead of processing them through an intermediate indentation fix.

Technical Impact

• Logic Simplification: By removing the automatic indentation fix, the replacement process is now more predictable and relies on the caller to provide correctly formatted replacement lines.
• Matching Accuracy: The change to sline.strip() not in code_lines[i + j].strip() ensures that the search logic is more robust against whitespace variations while maintaining strict adherence to the provided search patterns.
• Performance: Reduces overhead by eliminating unnecessary string manipulation and method calls during the replacement loop.