Use ahash for BUILTIN_INSTRUCTION_COSTS

[ksolana]

Fixes: #2196

Bench results:

$ ./cargo nightly bench --manifest-path cost-model/Cargo.toml

[tao-stones]

Looks good, do you have bench results to share?

[ksolana]

Benchmark Results

Baseline

test bench_hash_find ... bench:      30,955 ns/iter (+/- 756)
test bench_cost_model                       ... bench:   1,137,787 ns/iter (+/- 22,438)
test bench_cost_model_requested_write_locks ... bench:   1,174,591 ns/iter (+/- 12,127)
test bench_cost_tracker_contentious_transaction     ... bench:   1,831,908 ns/iter (+/- 122,044)
test bench_cost_tracker_non_contentious_transaction ... bench:   2,238,966 ns/iter (+/- 18,392)
test result: ok. 0 passed; 0 failed; 0 ignored; 2 measured; 0 filtered out; finished in 2.60s

With changes

test bench_hash_find ... bench:      19,944 ns/iter (+/- 656)
test bench_cost_model                       ... bench:     817,650 ns/iter (+/- 25,232)
test bench_cost_model_requested_write_locks ... bench:     885,115 ns/iter (+/- 6,901)
test bench_cost_tracker_contentious_transaction     ... bench:   1,831,225 ns/iter (+/- 32,081)
test bench_cost_tracker_non_contentious_transaction ... bench:   2,246,248 ns/iter (+/- 113,709)

[tao-stones]

thanks for adding bench, and the results look promising

[tao-stones]

lgtm