Use toasts for wiki notifications

What does this MR do?

Towards #26070 (closed).

Updates wiki pages to use toasts instead of alerts for wiki page creation, updates, and deletions.

Also updates wiki notification copy to be consistent across CRUD operations

Description	Old Copy	New Copy
Create wiki page	Wiki was successfully updated.	Wiki page was successfully created.
Update wiki page	Wiki was successfully updated.	Wiki page was successfully updated.
Delete wiki page	Page was successfully deleted	Wiki page was successfully deleted.

Screenshots (strongly suggested)

Before	After

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