[Tab Group Parity] Remove unbatching annotation on parity tests

Unbatching these tests is likely not the solution to the flakiness of
modal dialog related parity tests, so removing them.

Bug: 41490324
Change-Id: I331f59a92b53f67c6ab49c35bd755e96d79f137c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5405935


Reviewed-by: Sky Malice <skym@chromium.org>
Auto-Submit: Brandon Fong <bjfong@google.com>
Commit-Queue: Brandon Fong <bjfong@google.com>
Cr-Commit-Position: refs/heads/main@{#1279829}