Re-name Audit Log as Audit Events in UI and docs

What does this MR do?

This formally re-names Audit Log as Audit Events in multiple locations in the app, as the term Audit Events is already colloquially used to describe Audit Log. This is NOT a complete re-name, as this only changes the user-facing aspects. Renaming classes, files and variables would be executed under a future MR.

This does NOT include any functional changes, so should be easy to review.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Related to #292667