Remove precise terrain height json

[hpinkos]

Replaces #8244

As @mramato said in #8244, we can either fetch this file from our commit history or generate a new precise one when we need to.

[cesium-concierge]

Thanks for the pull request @hpinkos!

• ✔️ Signed CLA found.
• ❔ CHANGES.md was not updated.
  • If this change updates the public API in any way, please add a bullet point to CHANGES.md.
• ❔ Unit tests were not updated.
  • Make sure you've updated tests to reflect your changes, added tests for any new code, and ran the code coverage tool.

Reviewers, don't forget to make sure that:

• Cesium Viewer works.
• Works in 2D/CV.
• Works (or fails gracefully) in IE11.

[OmarShehata]

We should remove the optimizeApproximateTerrainHeights gulp task as well since then we'll just have a task that doesn't work without reverting this file from our commit history.

[hpinkos]

That makes sense @OmarShehata
Ready

[OmarShehata]

One more eslint error. Looks like we can get rid of the gulpJsonTransform library as well.