[Tab Group] Speculative fix for crash

Try disabling GroupNewTabWithParent to see if it fixes asserts.

I've been unable to repro; however, this feature makes sense to me as
being a possible cause (correct timing for landing and it is the only
novel behavior change to tab groups recently). If asserts don't fall off
I'll revert this CL.

Bug: 394394717
Change-Id: I691066a6d155d3085995c46cae79e780d2f61c0d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6235868
Commit-Queue: Calder Kitagawa <ckitagawa@chromium.org>
Reviewed-by: Sky Malice <skym@chromium.org>
Auto-Submit: Calder Kitagawa <ckitagawa@chromium.org>
Commit-Queue: Sky Malice <skym@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1416432}