Revert "[Windows] Add a sandbox string class for low-level heap allocations."

This reverts commit 2f89ea6c9429d9544f4bc9a0aba2940b0b235e9c.

Reason for revert: Crash during image file interception.

Original change's description:
> [Windows] Add a sandbox string class for low-level heap allocations.
>
> This CL adds a class to represent a low-level heap allocated string.
> In addition the class is then used in various NT utility functions
> which return strings with corresponding changes to the call sites for
> those utilities.
>
> Bug: 447171244
> Change-Id: Iaaa714707b4476582b34aa12a4e99522ec1a9a41
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7000096
> Reviewed-by: Alex Gough <ajgo@chromium.org>
> Commit-Queue: James Forshaw <forshaw@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1524571}

Bug: 447171244
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Change-Id: Ibadc37ebf602b7563e2835aea33c6cf48f9562f0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7003015
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: James Forshaw <forshaw@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1524670}