Cleanup some test code

[Robbepop]

We might also want to move the FuncType definition into the wasmi_core crate for reusability once we split up the workspace into many more smaller crates.

[paritytech-cicd-pr]

BENCHMARKS

	NATIVE			WASMTIME
BENCHMARK	MASTER	PR	DIFF	MASTER	PR	DIFF	WASMTIME OVERHEAD
execute/ bare_call_0	1.28ms	1.29ms	⚪ 0.30%	1.11ms	1.10ms	🔴 -1.20%	🟢 -15%
execute/ bare_call_0/typed	698.52µs	704.89µs	⚪ 0.87%	529.55µs	559.04µs	🔴 5.59%	🟢 -21%
execute/ bare_call_1	1.40ms	1.39ms	⚪ -0.41%	1.36ms	1.36ms	⚪ -0.23%	🟢 -3%
execute/ bare_call_16	2.97ms	2.97ms	⚪ -0.33%	5.11ms	5.11ms	⚪ 0.01%	🟡 72%
execute/ bare_call_16/typed	1.32ms	1.34ms	⚪ 1.67%	2.33ms	2.32ms	⚪ -0.45%	🟡 73%
execute/ bare_call_1/typed	806.59µs	815.26µs	⚪ 1.12%	870.40µs	876.85µs	⚪ 0.72%	🟢 8%
execute/ bare_call_4	1.78ms	1.78ms	⚪ 0.12%	2.15ms	2.15ms	⚪ -0.06%	🟢 21%
execute/ bare_call_4/typed	888.08µs	894.58µs	⚪ 0.63%	1.01ms	1.01ms	⚪ 0.21%	🟢 12%
execute/ br_table	939.93µs	923.48µs	🟢 -1.75%	1.12ms	1.12ms	⚪ -0.17%	🟢 22%
execute/ count_until	903.59µs	903.47µs	⚪ 0.00%	2.35ms	2.35ms	⚪ 0.21%	🔴 160%
execute/ factorial_iterative	365.73µs	377.14µs	🔴 3.08%	937.58µs	938.60µs	⚪ 0.13%	🔴 149%
execute/ factorial_recursive	728.87µs	760.78µs	🔴 4.49%	1.52ms	1.52ms	⚪ -0.18%	🟡 100%
execute/ fib_iterative	1.79ms	1.79ms	⚪ 0.06%	4.97ms	4.97ms	⚪ -0.04%	🔴 178%
execute/ fib_recursive	7.05ms	7.11ms	⚪ 1.00%	14.12ms	14.12ms	⚪ 0.13%	🟡 99%
execute/ global_bump	1.36ms	1.36ms	⚪ -0.05%	3.81ms	3.80ms	⚪ -0.07%	🔴 179%
execute/ global_const	1.00ms	1.00ms	⚪ 0.07%	2.77ms	2.79ms	⚪ 0.64%	🔴 178%
execute/ host_calls	32.68µs	32.66µs	⚪ -0.04%	44.94µs	44.26µs	⚪ -1.63%	🟢 35%
execute/ memory_fill	1.55ms	1.56ms	⚪ 0.13%	4.18ms	4.17ms	⚪ -0.17%	🔴 168%
execute/ memory_sum	1.55ms	1.55ms	⚪ -0.06%	4.15ms	4.15ms	⚪ 0.02%	🔴 168%
execute/ memory_vec_add	3.11ms	3.11ms	⚪ -0.09%	8.88ms	8.87ms	⚪ -0.10%	🔴 185%
execute/ recursive_is_even	1.31ms	1.32ms	⚪ 0.76%	2.60ms	2.65ms	🔴 2.14%	🔴 101%
execute/ recursive_ok	173.21µs	170.50µs	🟢 -2.39%	357.91µs	364.05µs	🔴 1.77%	🔴 114%
execute/ recursive_scan	214.02µs	214.50µs	⚪ 0.24%	466.56µs	468.09µs	⚪ 0.42%	🔴 118%
execute/ recursive_trap	17.04µs	16.90µs	⚪ -1.04%	35.85µs	36.74µs	🔴 2.48%	🔴 117%
execute/ regex_redux	668.00µs	674.44µs	⚪ 0.88%	1.59ms	1.60ms	⚪ 0.88%	🔴 137%
execute/ rev_complement	585.53µs	595.49µs	🔴 1.74%	1.55ms	1.55ms	⚪ -0.08%	🔴 160%
execute/ tiny_keccak	451.10µs	453.41µs	⚪ 0.85%	1.39ms	1.39ms	⚪ -0.27%	🔴 206%
execute/ trunc_f2i	1.07ms	1.07ms	⚪ 0.08%	2.56ms	2.53ms	⚪ -1.07%	🔴 136%
instantiate/ wasm_kernel	71.59µs	70.55µs	⚪ -1.91%	92.53µs	93.31µs	⚪ 0.55%	🟢 32%
translate/ wasm_kernel	4.17ms	4.18ms	⚪ 0.18%	7.89ms	7.79ms	⚪ -1.03%	🟡 86%

Link to pipeline