Auto merge of #14173 - eth3lbert:snapbox-f, r=weihanglo

test: mirgate fix* and future_incompat_report to snapbox

### What does this PR try to resolve?

Part of #14039.

Migrate following to snapbox:

- `tests/testsuite/fix.rs`
- `tests/testsuite/fix_n_times.rs`
- `tests/testsuite/future_incompat_report.rs`

Author: bors