[Parser] Clean up unused variables and emitted semicolons in asdl_c.py

[CoderSilicon]

Summary

This PR cleans up the code inside Parser/asdl_c.py by removing unused variable assignments that were cluttering the function scopes, and refactors trailing string-literal formatting to eliminate unneeded emitted semicolons in the generated AST output definitions.

Details

• Removed all unused trailing semicolons.
• Removed dead local variables inside AST node-visitor methods.
• Cleaned up redundant syntax emissions to make the generated C files more compliant.
• No corresponding tracking issue is attached as these are trivial code layout optimizations.

[python-cla-bot]

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[StanFromIreland]

Hello, as noted in the devguide, we do not accept PRs proposing solely cosmetic changes, this includes running a linter. Sorry, but I'm closing.