Add Check to SQL Update Statements to Avoid constraints on date_last_collected

[IsaacMilarky]

Description

• There was a bug where tasks that had succeeded in the past but then subsequently fail later would not be reset correctly; running into a constraint on 'date_last_collected'
• In response I have added checks to the date_last_collected field in order to prevent this issue
• Specifically we now check for null values in the date field and update to either SUCCESS or PENDING depending on if the field is null or not.
• The function now should reset the task to a state where it can be run again.

Signed commits

• Yes, I signed my commits.

[sgoggins]

LGTM