Updating logic for glic button icon based on panel state

The previous logic was to use attached icon when the panel was open.
This is jarring when we open the panel in attached state to see the icon
change. However, it is more inline with expectation to show the attached
icon only when the panel state is in detached state.

Bug: 392961107
Change-Id: Iaac74b60a9da9eae85e486cff4e787060bf5f255
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6263285
Reviewed-by: Andrea Gomez <andreaxg@google.com>
Commit-Queue: Eshwar Stalin <estalin@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1419984}