Cleanup Jelly flag logic in internet config dialog

Jelly has launched and this conditional code can be cleaned up. Also
removes associated tests.

Bug: b:319740292
Test: Manually verify dynamic colors supported in dialog
Change-Id: I9d4ca1df37ef762bf39a1f6fbfc7a98aeb3e7053
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5411460


Reviewed-by: Nikhil Nayunigari <nikhilcn@google.com>
Reviewed-by: Chad Duffin <chadduffin@chromium.org>
Commit-Queue: Wes Okuhara <wesokuhara@google.com>
Cr-Commit-Position: refs/heads/main@{#1282703}