[Passwods] Remove ellipses from password export buttons.

Mock: https://screenshot.googleplex.com/82XjL6Aw9REygf4
Implementation: https://screenshot.googleplex.com/7iNiZpWiJ8ixbfs.png
https://screenshot.googleplex.com/3vf8ChJoVNYKTeE.png

Bug: 1325290
Change-Id: I7b84aadca5eb0ea85b2d07d0e1ee70763165745a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3891273


Reviewed-by: Theodore Olsauskas-Warren <sauski@google.com>
Commit-Queue: Elias Khsheibun <eliaskh@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1045868}