Remove glTF 1.0 techniques from Photogrammetry Classification tileset

[ptrgags]

The 3D Tiles Photogrammetry Classification used a b3dm asset that uses glTF 1.0-style techniques (even though it was a glTF 2.0 model otherwise).

I manually converted the glTF asset to avoid using techniques (since those are deprecated). The Sandcastle linked above should work correctly (using Model).

Note that if you set enableModelExperimentalFeatures = true, the classification will not work because ClassificationModel does not yet work for ModelExperimental (it's an item on the roadmap: #10346), but it doesn't crash.

@j9liu could you review?

[cesium-concierge]

Thanks for the pull request @ptrgags!

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Reviewers, don't forget to make sure that:

• Cesium Viewer works.
• Works in 2D/CV.

[j9liu]

@ptrgags looks good -- I confirmed that Model behaves just the same, and it doesn't cause a crash anymore for ModelExperimental. Thanks!