input_chunk: routes_mask is not initialized (#10223)

[jinyongchoi]

This patch fixes an issue where routes_mask was not initialized, leading to potential errors, by adding the necessary initialization code.

Closes #10223

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Testing
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• Attached Valgrind output that shows no leaks or memory corruption was found

==119424== 
==119424== HEAP SUMMARY:
==119424==     in use at exit: 0 bytes in 0 blocks
==119424==   total heap usage: 16,898,665 allocs, 16,898,665 frees, 17,168,835,647 bytes allocated
==119424== 
==119424== All heap blocks were freed -- no leaks are possible
==119424== 
==119424== For lists of detected and suppressed errors, rerun with: -s
==119424== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

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