[common] Use `std::make_unique_for_overwrite<T>` in ScratchBuffer, remove polyfill (#4432)

Original `make_unique_for_overwrite.h` is well defined acc. to standard https://en.cppreference.com/cpp/memory/unique_ptr/make_unique, but by now most libc++ supports the function, so no need for polyfill.

Test that this didn't break anything (for example, Megaman game that has video at the start), or anything using VIC/IPC.

Signed-off-by: lizzie <lizzie@eden-emu.dev>

- [x] I have read and followed the [Contribution Guidelines](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/CONTRIBUTING.md#code-contributions).
- [x] I have read and followed the [AI Policy](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/docs/policies/AI.md)
- [x] I have read and followed the [Coding Guidelines](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/docs/policies/Coding.md) to the best of my ability.

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Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/4432
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>

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