[EducationalTip] Update educational tip cards' logos and talkback of default browser bottom sheet

This CL makes the following updates:
1. Updates the logo on the tab group sync promo card to a new design.
2. Changes the color of the logos on all educational tip cards in dark
mode.
3. Modifies the string/attributes associated with the talkback
function for the default browser bottom sheet.

The new logos are illustrated in the following doc:
https://docs.google.com/document/d/1ljR6br1dhznkmXQ1FfT1xBaZ12931qvrq78Vh9-8-dQ/edit?usp=sharing&resourcekey=0-gD3hg0r1FrRpBv2hq9Xlug

The following links show the current talkback design for the default
browser bottom sheet:
1. Talkback triggered when click the whole bottom sheet:
https://drive.google.com/file/d/1_ObYxUy98pbSf7CbZlBMrgEnN-PU_Hgv/view?usp=sharing&resourcekey=0-lJkJRBEgQ6FCXBJH-zaW5w
2. Talkback triggered when click the steps of the bottom sheet:
https://drive.google.com/file/d/1LH7iy-N-PjHUlcYXTYIb8uzznHxaVD3f/view?usp=sharing&resourcekey=0-cyc3brBhG7ds5f68dH5pNg
3. Talkback triggered when scroll the bottom sheet partially:
https://drive.google.com/file/d/1XuBtpe56YDFKStWSt0febMUSG1aVlMEE/view?usp=sharing&resourcekey=0-czI_KDWmImJUZCyVL8COZA
4. Talkback triggered when close the bottom sheet:
https://drive.google.com/file/d/1mzwxg0hvafbDa1BrnxTNcYMGQcewjjwV/view?usp=sharing&resourcekey=0-VjwNTZJU5E8aL5gLb4oWsg

Bug: 355015904
Change-Id: Ief2833989596416d7c6cbe7175d551a9c077309e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6216368
Reviewed-by: Theresa Sullivan <twellington@chromium.org>
Commit-Queue: Xinyi Ji <xinyiji@chromium.org>
Reviewed-by: Xi Han <hanxi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1414068}