Sort Value Stream Analytics event names

What does this MR do?

This MR sorts the VSM event names alphabetically.

• Additional change: Make event names consistent, Merge Request -> Merge request
• Fix the wrong name for production stage end.
• Test improvement: Use explicit event identifiers when selecting events from the dropdown in the stage form tests.

Screenshots

Here is what the list looked like previously, with list items basically un-ordered:

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