promtail update to 6.15.3-bb.4

General MR

Summary

Promtail istio Authz policy testing

big-bang/product/packages/promtail!55 (merged)

big-bang/product/packages/promtail!57 (merged)

Linked Issue

Closes big-bang/product/packages/promtail#34 (closed)

Upgrade Notices

N/A