profiling: investigate chunks with start/end sample duration much longer than 1 min

[armcknight]

Description

The chunks should be serialized at 1 min intervals, but we see some trunks that contain samples with timestamps much later than one minute from the initial sample. Our guess is that we don't always perfectly shut down the profiler on app background, so that when it's for grounded again, it resumes adding samples to the last chunk that was in flight.

See if we can reproduce this, and then we can consider how to handle it, maybe on foreground we make some additional checks and handling of the data structures.