chore: TR-479 Remove decaffeinate tasks

[jennifer-shehane]

TR-479

• close chore: Remove decaffeinate tasks and some other leftover references to coffeescript #9125

Removes decaffeinate tasks since the last of CoffeeScript files (outside of testing CoffeeScript itself) has been removed.

[cypress-bot]

Thanks for taking the time to open a PR!

• Create a Draft Pull Request if your PR is not ready for review. Mark the PR as Ready for Review when you're ready for a Cypress team member to review the PR.
• Become familiar with the Code Review Checklist for guidelines on coding standards and what needs to be done before a PR can be merged.

[cypress]

---

Test summary

9197 • 0 • 118 • 3 • 1

---

Run details

Project	cypress
Status	Passed
Commit	ad2390a
Started	Jan 19, 2021 6:13 AM
Ended	Jan 19, 2021 6:25 AM
Duration	12:26 💡
OS	Linux Debian - 10.5
Browser	Multiple

View run in Cypress Dashboard ➡️

---

Flakiness

	cypress/integration/retries.ui.spec.js		1
1	runner/cypress retries.ui.spec > opens attempt on each attempt failure for the screenshot, and closes after test passes

---

This comment has been generated by cypress-bot as a result of this project's GitHub integration settings. You can manage this integration in this project's settings in the Cypress Dashboard