Revert "Update Viewer on preUpdate instead of clock tick"

[lilleyse]

Fixes #7081

Reverts #7069 until there is a guaranteed fix for #6934 (comment), which may look like this but may not.

[cesium-concierge]

Thanks for the pull request @lilleyse!

• ✔️ 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.

Reviewers, don't forget to make sure that:

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

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[hpinkos]

Thanks @lilleyse!