refactor(prettier): Update tasks/prettier to correctly handle snapshots

[leaysgur]

I refactored the code in tasks/prettier_conformance primarily to make the output more readable when using --filter.

But I also discovered that our previous implementation did not correctly handle Prettier's behavior of adding a blank line at the EOF.

In addition, I resolved a problem where test specs that used patterns like runFormatTest(_, parsers) were unable to locate the correct snapshot output.

As a result, compatibility has also improved slightly. 😉

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[codspeed-hq]

CodSpeed Performance Report

Merging #8337 will not alter performance

_{Comparing p/tasks (d59ef64) with main (a76dfae)}

Summary

✅ 29 untouched benchmarks

[Boshen]

Nice!