Remove whenever gem, configuration, and secret requirement

[davemcorwin]

This is unused and we typically won't be using cron jobs in idp in favor of CloudWatch Scheduled Events.

See LG-408 for removal off secrets from application.yml

Hi! Before submitting your PR for review, and/or before merging it, please
go through the following checklist:

• For DB changes, check for missing indexes, check to see if the changes
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