Update widget on click dropdown item when creating epic from epic

What does this MR do?

When a user selects create new epic or issue from the drop down on an epic, the widget automatically updates with the relevant fields and options to create those objects. Current functionality is clicking the drop down to select Create new issue/epic and then having to click the Create new issue/epic button again to get the fields to update.

Screenshots

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

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

Issue #119341 (closed)