Remove 1.57 deprecation warnings

[OmarShehata]

This removes the deprecation warnings for fetchImage #7630 and followSurface #7504.

@tfili

[cesium-concierge]

Thanks for the pull request @OmarShehata!

• ✔️ 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.

[tfili]

@OmarShehata You have 2 failing tests.

Also, thanks for getting to these.

[OmarShehata]

@tfili I ended up having to not just remove followSurface from the public API, but also all uses internally, because otherwise, the constructor no longer accepted the option, but you could then set it on a polyline directly and it would work.

So I removed it, and updated the tests. Two tests were completely removed:

• PolylineGeometrySpec.js / constructor converts followSurface to arcType, because it was testing whether the constructor correctly converts this deprecated option.
• PolylineGeometryUpdaterSpec.js / followSurface true with undefined globe does not call generateCartesianArc, because it was just a duplicate of the test below it for followSurface instead of arcType.

I did NOT remove anything in the CZML adapting the option because that's intentionally there for backwards compatibility. The polyline Sandcastles seem to work correctly.