Revert "[Autofill] Encrypt values of attribute instances"

This reverts commit 90086951569d10ef7a632acf3238aaf3b8a527df.

Reason for revert: Parent of CL is likely culprit for build failures,

Bug: 392818482

Original change's description:
> [Autofill] Encrypt values of attribute instances
>
> This CL encrypts attribute instance values.
>
> It's a breaking change to the database schema. That is OK because the
> rollout hasn't started yet. Developers can wipe the database with
> --autofill-wipe-entities.
>
> Bug: 388590912
> Change-Id: I19b8183592a9adbe1150ed334a298f38fac7ceff
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6203402
> Reviewed-by: Jan Keitel <jkeitel@google.com>
> Commit-Queue: Christoph Schwering <schwering@google.com>
> Cr-Commit-Position: refs/heads/main@{#1412190}

Bug: 388590912
Change-Id: I6b6d262c418e1e490c6e8e82054446063d793532
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6206807
Auto-Submit: Florian Jacky <fjacky@chromium.org>
Commit-Queue: Florian Jacky <fjacky@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Owners-Override: Florian Jacky <fjacky@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1412210}