Update Ironbank to v2.8.0

This MR contains the following updates:

Package	Update	Change
ironbank/opensource/grafana/promtail	minor	v2.7.5 -> v2.8.0
ironbank/opensource/grafana/promtail	minor	2.7.5 -> v2.8.0
registry1.dso.mil/ironbank/opensource/grafana/promtail	minor	v2.7.5 -> v2.8.0

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