Promtail update to 6.15.5-bb.0

Package Merge Request

Package Changes

• Updated ironbank/opensource/grafana/promtail v2.9.2 -> v2.9.4
• Updated registry1.dso.mil/ironbank/opensource/grafana/promtail v2.9.2 -> v2.9.4
• Updated chart version to 6.15.5

Package MR

big-bang/product/packages/promtail!50 (merged)

For Issue

Closes big-bang/product/packages/promtail#30 (closed)

Upgrade Notices

N/A