Remove effect attribute from tests

[jovyntls]

What is the purpose of this pull request?

• Documentation update
• Bug fix
• Feature addition or enhancement
• Code maintenance
• Others, please explain:

Overview of changes:
Remove the use of the effect attribute in the tests, as it is not implemented and has no effect.
Related changes to the documentation were made in #1777

Anything you'd like to highlight / discuss:
N/A

Testing instructions:
N/A

Proposed commit message: (wrap lines at 72 characters)

Remove unused effect attribute from tests

Currently, the effect attribute is not implemented for both popovers 
and tooltips. However, it is included in some of the tests for these 
components. This may be confusing and clutter the codebase. 

Let's remove the effect attribute from these tests, to avoid confusion 
on whether or not this is a valid attribute.

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Checklist: ☑️

• Updated the documentation for feature additions and enhancements
• Added tests for bug fixes or features
• Linked all related issues
• No unrelated changes

[ryoarmanda]

LGTM!