adjust symptom onset handling

[mikehelmick]

Proposed Changes

• "unreasonable" symptom onset intervals < 28d ago by default will be treated as if 0 is passed in.
• keys with a valid symptom onset interval but fall outside the range of -14d..14d will be dropped (restores old / correct behavior.) THIS IS A CHANGE - currently those keys would get adjusted to nil, which would cause default
• if NO symptom onset date is passed in, we tread the symptom onset day as 4 days ago and adjust the data on the TEKs accordingly

This modeling is being adjusted in consultation with the Apple+Google clinical teams working on EN.

Release Note

BEHAVIOR CHANGE: The handling of symptom onset intervals is changing. Any symptom onsets older than 28 days ago (rounded down to UTC midnight) will be treated as invalid and as if 0 was passed in. Keys with a valid symptom onset days outside of -14..14 will be dropped. If there is not symptom onset passed, the symptom onset interval is set to 4 days ago.
Timing flags can be adjusted via environment variables. Default values are recommended.

[mikehelmick]

/hold
until monday - want to give people a chance to comment

[mikehelmick]

/hold cancel

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