Fix for zero average order value on charts #19353

Description:

Fixes #15262

The average order value on the evolution overview charts was always shown as zero, this was caused by pre-formatted values in the datatable breaking the jqplot data generation.

This fix attempts to solve this by:

• Respecting evolution chart visualization calls which set format_metrics = 0 (only setting a format_metrics default value if there are no request override parameters)
• Having evolution charts set format_metrics = 0
• Passing the series units to the jqplot data generation setAxisYValues method
• If the series unit is a percent then convert chart data values to display percentages.
• jqplot chart number formatting currently doesn't fully support internationalization (eg. forcing a dot as a decimal point separator), all series formatting units were being added as a postfix, I added a minor tweak to show dollar and pound currency symbols as prefixes. This is obviously not ideal but should be a slight improvement for some people, if we had a reliable way to determine the currency symbol position then we could possibly add that as metadata to core/Metrics::getUnit() and make it available to the jqplot formatting code.

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