Revert "[sheriff] Disable LoginOfflineManagedTest.LoginAllowlistedUser"

This reverts commit 33e93243561751ab8245520a915c9a59bfe97512.

Reason for revert: the failures seem to be caused by CLs reverted in https://chromium-review.googlesource.com/c/chromium/src/+/3105888 

Original change's description:
> [sheriff] Disable LoginOfflineManagedTest.LoginAllowlistedUser
>
> Bug: 1240601
> Change-Id: Idcd6b3b5b2637c858c80d73b7690313880167ef9
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3114345
> Owners-Override: Xida Chen <xidachen@chromium.org>
> Auto-Submit: Xida Chen <xidachen@chromium.org>
> Reviewed-by: Ella Ge <eirage@chromium.org>
> Commit-Queue: Xida Chen <xidachen@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#914380}

Bug: 1240601
Change-Id: I62c49cae54bec733cf82220c7f4e70e2e424371d
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3114130
Auto-Submit: Roman Sorokin [CET] <rsorokin@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Reviewed-by: Ella Ge <eirage@chromium.org>
Cr-Commit-Position: refs/heads/main@{#914453}