Revert "[lensoverlay] Reenable SelectionOverlay tests"

This reverts commit 4c3feaba028fa065fd135f95f97a1908b15a0a45.

Reason for revert: Still flaky https://ci.chromium.org/ui/p/chromium/builders/ci/Linux%20Tests%20(dbg)(1)/123768/overview

Original change's description:
> [lensoverlay] Reenable SelectionOverlay tests
>
> The tests were disabled due to flakiness. They stayed disabled for so
> long that they eventually became broken. I fixed the tests and am
> reenabling. If they are still flaky, I will fix ASAP.
>
> One test that verified the user can drag a post selection corner over a
> word bounding box was failing because the feature was broken, so I fixed
> the feature rather than changing the test.
>
> Change-Id: I349c4c32c350c840b9374b5f069a62d7aeda2517
> Fixed: 383376596
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6085839
> Reviewed-by: Juan Mojica <juanmojica@google.com>
> Commit-Queue: Duncan Mercer <mercerd@google.com>
> Cr-Commit-Position: refs/heads/main@{#1395026}

Change-Id: I8d39881fee10a88c56d0b11db4f2258ebe19a641
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6088655
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Owners-Override: Ken Okada <kenoss@chromium.org>
Commit-Queue: Ken Okada <kenoss@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1395261}