Remove deprecated attachToDocument

What does this MR do?

@vue/test-utils 1.x will deprecate attachToDocument

To fix that we introduce new createDisposableMountPoint helper which will create DOM Node and automatically dispose it after test

(Most of the tests no more need attachToDocument so most of them are just silently removed)

Screenshots

N/A

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