fix https://github.com/brave/brave-browser/issues/26091
Below upstream's change enabled underline.
https://chromium-review.googlesource.com/c/chromium/src/+/3855278
WebUI: Decorate links with underline
This is part 1 of decorating all links and all buttons that look like
links with the underline to help users better differentiate between
normal text and actionable links. This CL updates links on Settings,
Extensions, Management, Downloads, and Welcome, as well as updating
a couple of global WebUI styles.
Simon Hong
1a9cb91af5