Revert "Reland "Model validation support""

This reverts commit d8bf9f5d.

Reason for revert: 
ModelValidatorExecutorTest.InvalidModel test fails after this CL:
https://ci.chromium.org/p/chromium/builders/ci/Linux%20MSan%20Tests

Original change's description:
> Reland "Model validation support"
>
> This is a reland of 155e38f8
>
> Removed the browser tests that were failing in chrome OS.
>
> > Model validation support
> >
> > Introduces a ModelValidator class and adds a command-line switch to
> > validate model using ModelValidator. No code is expected to run when the
> > command-line switch is not specified.
>
> > Bug: 1219668
> > Change-Id: I12f93956b4657bb9997b772a797f1e37d2e99a03
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2999073


> > Reviewed-by: Tommy Nyquist <nyquist@chromium.org>
> > Reviewed-by: Sophie Chang <sophiechang@chromium.org>
> > Commit-Queue: rajendrant <rajendrant@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#908596}
>
> Bug: 1219668
> Change-Id: I1f5643215942902d2920a04b84697c6b3b7ec112
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3111963


> Reviewed-by: Sophie Chang <sophiechang@chromium.org>
> Reviewed-by: David Trainor <dtrainor@chromium.org>
> Commit-Queue: rajendrant <rajendrant@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#915065}

Bug: 1219668
Change-Id: Ifd972a71cd7b7c90ac018759bba339466eee57ca
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3117805
Auto-Submit: Michael Ershov <miersh@google.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Michael Ershov <miersh@google.com>
Owners-Override: Michael Ershov <miersh@google.com>
Cr-Commit-Position: refs/heads/main@{#915151}