Revert "Use last committed URL to open new tab links in side panel."

This reverts commit 112a25c1db921056ef5d7d8dcc97612750bb7db3.

Reason for revert: Suspected to cause chrome os failures, see https://ci.chromium.org/ui/p/chrome/builders/ci/linux-chromeos-chrome/18065/test-results and https://bugs.chromium.org/p/chromium/issues/detail?id=1260340

Original change's description:
> Use last committed URL to open new tab links in side panel.
>
> Bug: 1255214, b:201790284, b:201789654, b:201802516
> Change-Id: I2ee5697a4b8ecfdbed2bc5a9946d0fa3ad58dcb9
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3198114
> Reviewed-by: Adam Langley <agl@chromium.org>
> Reviewed-by: Ben Goldberger <benwgold@google.com>
> Reviewed-by: Mike Wasserman <msw@chromium.org>
> Commit-Queue: Juan Mojica <juanmojica@google.com>
> Cr-Commit-Position: refs/heads/main@{#931785}

Bug: 1255214, b:201790284, b:201789654, b:201802516
Change-Id: I7d708c94008a077c158cfee41ef0ee48dcdbd9f5
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3225888
Owners-Override: Dominik Röttsches <drott@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Anders Hartvoll Ruud <andruud@chromium.org>
Auto-Submit: Dominik Röttsches <drott@chromium.org>
Reviewed-by: Anders Hartvoll Ruud <andruud@chromium.org>
Cr-Commit-Position: refs/heads/main@{#931982}