Revert "[UPMLoginDbSunset] Add fieldtrial testing config for the login db"

This reverts commit b3413ed4da7ef2b4e2eb60a269a1c00af5a6fd2a.

Reason for revert: crbug.com/407093342, broke many tests in arm64

Original change's description:
> [UPMLoginDbSunset] Add fieldtrial testing config for the login db
>
> And disable the feature for tests that are no longer relevant after the
> login db deprecation.
>
> Bug: 406741732
> Change-Id: Id4ab59f91fb9caf70a09878fabb09294e4193f58
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6392716
> Reviewed-by: Gang Wu <gangwu@chromium.org>
> Reviewed-by: Anna Tsvirchkova <atsvirchkova@google.com>
> Commit-Queue: Ioana Pandele <ioanap@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1439564}

Bug: 406741732,407093342
Change-Id: I2c695cee10519fea7bdf98f53e41ee8f074120dc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6410054
Owners-Override: Henrique Nakashima <hnakashima@chromium.org>
Reviewed-by: Min Qin <qinmin@chromium.org>
Auto-Submit: Henrique Nakashima <hnakashima@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Reviewed-by: Yue Zhang <yuezhanggg@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1439776}