Jestify some specs that start with "A"

What does this MR do?

This MR moves the following specs to Jest:

• spec/javascripts/activities_spec.js
• spec/javascripts/api_spec.js
• spec/javascripts/autosave_spec.js

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.