Make page performance overlay work with flattened reports

[sgiehl]

Description:

Pages reports provide a row action that will open the page performance report for a specific row. When viewing any action report in normal view that works like a charm. But when the report is changed to be flattened the overlay doesn't show any data anymore.

The reason for this is, that the API request performed for the overlay didn't get the flat parameter passed through. This causes the provided label (action url) not to be found in the report.

Passing through the flat parameter fixes this problem and the data is displayed correctly again.

fixes #17807

Review

• Functional review done
• Potential edge cases thought about (behavior of the code with strange input, with strange internal state or possible interactions with other Matomo subsystems)
• Usability review done (is anything maybe unclear or think about anything that would cause people to reach out to support)
• Security review done
• Wording review done
• Code review done
• Tests were added if useful/possible
• Reviewed for breaking changes
• Developer changelog updated if needed
• Documentation added if needed
• Existing documentation updated if needed