Fix missing charts for imported test history

Runs uploaded with an older start date, such as imported history or a migration from another system, were missing from the Measurement Control charts and filters even though the measurement table below listed them.

• Fixed backdated runs not appearing in measurement analytics: charts, trends and sidebar filters now include them as soon as the data is uploaded
• Improved how historical data is folded into the pre-computed analytics so charts stay fast once the import settles