Create new sec finding partition if old partition grows stale

What does this MR do and why?

This MR updates the logic for security finding partitions to ensure that a new partition is created if the current partition exceeds 100GB as it already does, but also if the oldest finding in the partition is more than the retention period duration old. (90 days self managed, 30 days on GitLab.com).

This should ensure that the partition gets cycled eventually without needing to reach 100GB in size first. This should prevent disk saturation risks for self managed instances that see lower usage and may be deployed on smaller disks.

References

Resolves #569397 (closed)

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