Revert "WebNN: support constant tensors"

This reverts commit fd00312e80a964f7f5dffee1f811f634f7fe731e.

Reason for revert: See bug

Bug: 418078503
Original change's description:
> WebNN: support constant tensors
>
> Allows MLTensor to be input to constant() so weights can be
> reused on-device between multiple builds on the same builder
> or different builders. This eliminates the need to keep the original
> JS input data and lowers CPU memory usage.
>
> To keep the CL size in check, only the DML backend was enabled.
>
> More specifically:
> * Adds constant usage to MLTensor.
> * Allows tensors to be initialized from a supplied JS buffer.
> * Supports graph builds using weights from tensors.
>
> Restrictions:
> * Constant tensors cannot be dispatched.
> * Constant tensors must be initialized.
> * Constant tensors must remain static.
>
> https://github.com/webmachinelearning/webnn/issues/760
>
> Bug: 332350952
> Change-Id: Ib18dfe06ead6728172355f2a540e3faeec99917b
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6075601
> Reviewed-by: Alex Gough <ajgo@chromium.org>
> Reviewed-by: Reilly Grant <reillyg@chromium.org>
> Commit-Queue: Bryan Bernhart <bryan.bernhart@intel.com>
> Cr-Commit-Position: refs/heads/main@{#1460981}

Bug: 332350952
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Change-Id: I01c02f3fafef3d68f483f88e30fc5fc7a5d70740
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6552231
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Owners-Override: Stefan Zager <szager@google.com>
Cr-Commit-Position: refs/heads/main@{#1461097}