refactor: use C++20 string::{starts,ends}_with

[scarf005]

Checklist

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Purpose of change

code is liability; replace them with functions available in C++20 stdlib since we have #5514

Describe the solution

• use C++20 features like https://en.cppreference.com/w/cpp/string/basic_string/starts_with
• remove obsolete benchmarks

Describe alternatives you've considered

Testing

Additional context

[OrenAudeles]

looks good to me