[php-src] PR #22988: tests: applied fixers to improve test robustness

Pull Request: https://github.com/php/php-src/pull/22988 Author: NickSdot Hey! As requested in https://github.com/php/php-src/pull/22799#issuecomment-5124595234 I carry over commits into separate PRs for extensions (or in this case the shared tests directory). This was cherry picket from https://github.com/php/php-src/pull/22799 (where the deterministic proof is). I manually reviewed the diff, to make sure it doesn't infer with the ongoing style discussion that affects other parts. This one has five (5) unaffected style-only changed lines. Moderate, hence, IMO safe to merge independently. The more individual extension PRs are merged, the smaller the diff in the main PR, the easier to review. Merging this one will decrease diff size in the main PR by ~601 lines (~3.8%), and will decrease its affected files by 55 files (~2%).