[WPB-8881] Add unit tests for new effect actions

[mdimjasevic]

This is a follow-up PR to #4316 that adds unit tests for effect actions that were introduced in that PR.

Tracked by https://wearezeta.atlassian.net/browse/WPB-8881

Checklist

• [x] Add a new entry in an appropriate subdirectory of changelog.d
• [x] Read and follow the PR guidelines

[mdimjasevic]

@supersven , is there anything else you'd like me to change, update, or do about it?