Revert "Re-enabling safari unit tests on Mac."

This reverts commit 3aa78f4c3b61a467556dcb7b6a4700b05535655d.

Reason for revert: Even though these tests passed on try bots on the times that I run them. They still fail on half of the prod bots. My theory is the Safari versions on the bots are different. The bots who fail the tests always fail. We don't have a clear solution to this with the existing safari solution (using pre-installed safari). One option can be to update all safari versions of the bots. Another option can be to use Webkit release (and use a fixed version from a cipd package) instead of Safari. Both needs more work so reverting this change.

PR also fixes the expectations to resolve the merge conflicts.

Original change's description:
> Re-enabling safari unit tests on Mac.
>
> Killing open Safari processes before and after the tests.
>
> Change-Id: I064167414c34a69af249a22fbcb17c3c8bde29dd
>
> Example run: https://chromium-swarm.appspot.com/task?id=4cae14304fad9f10
>
> I run this 4 times, I didn't get any flakes/test errors.
>
> Change-Id: I064167414c34a69af249a22fbcb17c3c8bde29dd
> Reviewed-on: https://flutter-review.googlesource.com/c/recipes/+/3500
> Reviewed-by: Christopher Fujino <fujino@google.com>
> Commit-Queue: Nurhan Turgut <nurhan@google.com>

TBR=godofredoc@google.com,flutter-scoped@luci-project-accounts.iam.gserviceaccount.com,fujino@google.com,nurhan@google.com

Change-Id: I858eec768660031f26983d3be4c301e4b9b76b95
Reviewed-on: https://flutter-review.googlesource.com/c/recipes/+/3520
Reviewed-by: Nurhan Turgut <nurhan@google.com>
Reviewed-by: Godofredo Contreras <godofredoc@google.com>
Commit-Queue: Godofredo Contreras <godofredoc@google.com>