test(types): cover iotracing wire schema

[Loyal-Young]

Summary

• Add IO tracing wire-schema round-trip coverage for process file statistics and scheduler stall stacks.

Validation

• git diff --check

[hao022]

@Loyal-Young 感谢贡献代码。这个测试可以参考pkg/types/dropwatch_test.go 1. 使用 table-driven tests 2. 使用 cmp.Diff 比较结果。