Add EPSS mirroring when NVD mirroring is not active

[PetervantHoff]

Current Behavior

We use trivy as a scanner for vulnerabilities for our container images. Because NVD overwrites these vulnerabilities when NVD mirroring is enabled and it also leads to more vulnerabilities (we use RedHat based containers and NVD does not take Red Hat specific versions into account).
However EpssMirrorEvent is only triggered after the NVD mirroring. Therefor we have no EPSS scores when NVD mirroring is not active.

Proposed Behavior

Trigger EPSS mirroring after the trivy analysis or on a daily schedule if NVD mirroring is not active.

Checklist

• I have read and understand the contributing guidelines
• I have checked the existing issues for whether this enhancement was already requested