[Discounts] Allow flex layout view to adjust height for width

This CL fixes the wrapping issue of the discount disclaimer label. It's
a multi-line label, but it was rendered as single line. This CL fixes
the issue.

Screenshot before: https://screenshot.googleplex.com/Ao6szuo5ox2keVo
After: https://screenshot.googleplex.com/9VJUowo4YXc4Mbc

Bug: 1494224
Change-Id: Id8ba65dc03bb5eae430fe333010d36e84d9f3d3f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4957516
Commit-Queue: Mei Liang <meiliang@chromium.org>
Reviewed-by: Emily Shack <emshack@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1212854}