Skip build/rebuild when serving in release zip

[ggetz]

• Fixes Static npm start inside release ZIP file #10611 by including a "production" flag in server.js which skips the build/rebuild process. The flag is included in the modified package.json which we create for the release zip as part of make-zip.
• I noticed the Spec files were no longer packaged in the release zip. Although they should be omitted from the nom packages, they should be included in the release zip so that test can be run in both the browser and on the command line. See discussion in Fix gulpfile tasks in release zip, but limit packaged scripts #10311.

(Most of the changes here are whitespace changes. You can ignore with the PR code display settings.)

[cesium-concierge]

Thanks for the pull request @ggetz!

• ✔️ 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.

[sanjeetsuhag]

Changes look good. Thanks @ggetz!