Tip Router: Fix stack frame initialize_weight_table

[aoikurokawa]

We currently have issue with initialize_weight_table:

cargo-build-sbf --dump

Error: Function _ZN23jito_tip_router_program23initialize_weight_table31process_initialize_weight_table17h6eb3696e2ef38ac9E Stack offset of 6688 exceeded max offset of 4096 by 2592 bytes, please minimize large stack variables. Estimated function frame size: 6880 bytes. Exceeding the maximum stack offset may cause undefined behavior during execution.

By shifting the logic out of the main function, stack size usage in the main function is reduced, which helps to prevent stack overflow errors, i think.

At least after fixing, i dont see the error and test still passes.

[ebatsell]

Addressed in #20