[CCT][ToolbarRefactor] Fix optional button icon/bg state image position

The button icon was 2dp off the center wrt the background image, and
the pressed-state image was not positioned/scaled correctly. This CL
fixes that.

Note: pressed-state ListDrawable is set after the optional button is
first updated. It had to be moved accordingly.

Before: https://drive.google.com/file/d/1EN_gIVZHzs2IjZmfGJCTv3qBsAnuIpW8/view?usp=sharing
After: https://drive.google.com/file/d/1QhDoINKuzyFxgs3Ac3ccF6nrdDllAoB9/view?usp=sharing

Bug: 428261559
Change-Id: I8722f6ee1dff01526e9f4e44cb9c7edf5f185037
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6828360
Reviewed-by: Sinan Sahin <sinansahin@google.com>
Commit-Queue: Jinsuk Kim <jinsukkim@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1499067}