Revert "[iOS] Fix Add to Group in TabGrid selection"

This reverts commit 9a550abf.

Reason for revert: broke IOS build (https://ci.chromium.org/ui/p/chromium/builders/ci/ios-device/351227/overview)

Reverted while gardening to re-open the tree.

Original change's description:
> [iOS] Fix Add to Group in TabGrid selection
>
> If shareable and non-sharable tabs are selected, they should all be
> movable to new or existing tab group using the selection mode in the
> TabGrid.
>
> Fixed: 331745630, 328425613
> Change-Id: Ia9277351e4a3530b67f0fe95facf14876fa5ec05
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5401801


> Auto-Submit: Gauthier Ambard <gambard@chromium.org>
> Reviewed-by: Louis Romero <lpromero@google.com>
> Commit-Queue: Gauthier Ambard <gambard@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1280134}

Change-Id: Ief625bf17dece646faa24264ccbba2695ec51bb0
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5402519


Reviewed-by: Noam Rosenthal <nrosenthal@chromium.org>
Commit-Queue: Noam Rosenthal <nrosenthal@chromium.org>
Owners-Override: Noam Rosenthal <nrosenthal@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1280136}