[Autofill Assistant] Fixed small bugs in payment request.

This fixes a bug with the chevron alignment and also a bug where the last (rather than the first) complete item was preselected in some cases.

Screenshot after change (chevron in payment method is now vertically centered): https://screenshot.googleplex.com/buOn4neaRxZ.png

(cherry picked from commit 6b430bef37bcdc76dce002b853e293c47fefefab)

Bug: 990798
Bug: b/138643986
Bug: b/138643669
Change-Id: Idf61e667a5290a2314d3d95d62f45cab9e0e0bc3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1729227
Auto-Submit: Clemens Arbesser <[email protected]>
Reviewed-by: Jordan Demeulenaere <[email protected]>
Commit-Queue: Jordan Demeulenaere <[email protected]>
Cr-Original-Commit-Position: refs/heads/master@{#682738}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1741673
Cr-Commit-Position: refs/branch-heads/3865@{#257}
Cr-Branched-From: 0cdcc6158160790658d1f033d3db873603250124-refs/heads/master@{#681094}
2 files changed