Revert "Verify extension location in CheckExternalUninstall"

This reverts commit e191a7dd133404ead97c9c37ef6d142fd63f0009.

Reason for revert: High-confidence culprit for crbug.com/400001079.

Original change's description:
> Verify extension location in CheckExternalUninstall
>
> The ExtensionService::CheckExternalUninstall function is called to make
> sure that external extensions that are no longer acknowledged by any
> external provider are uninstalled. Since the location value isn't
> checked, an extension that's assigned with one location value, and also
> registered in another external provider, won't be uninstalled. Check the
> location value as well, such that an external provider is only taken
> into account if it's aware of both the extension id and the location
> value.
>
> Bug: 397903880
> Change-Id: Ifd7e9237d86d52a9c7f31895fe35a86383579ac1
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6304748
> Reviewed-by: Reilly Grant <reillyg@chromium.org>
> Auto-Submit: Michael Maltsev (R&D) <michaelm@island.io>
> Commit-Queue: Michael Maltsev (R&D) <michaelm@island.io>
> Reviewed-by: Devlin Cronin <rdevlin.cronin@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1425605}

Bug: 397903880, 400001079
Change-Id: Iddaf6f0047387c67e4b17cc35823d987a72b6554
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6315270
Commit-Queue: Reilly Grant <reillyg@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1426770}