Merge branch 'update-loki-tag-5.31.0-bb.0' into 'master'

loki update to 5.31.0-bb.0 & promtail update to 6.15.3-bb.0

Closes big-bang/product/packages/loki#66 and big-bang/product/packages/promtail#28

See merge request !3339

chart/values.yaml

@@ -662,7 +662,7 @@ promtail:
   git:
     repo: https://repo1.dso.mil/big-bang/product/packages/promtail.git
     path: "./chart"
-    tag: "6.15.0-bb.3"
+    tag: "6.15.3-bb.0"
   helmRepo:
     repoName: "registry1"
     chartName: "promtail"
@@ -687,11 +687,11 @@ loki:
   git:
     repo: https://repo1.dso.mil/big-bang/product/packages/loki.git
     path: "./chart"
-    tag: "5.23.1-bb.2"
+    tag: "5.31.0-bb.0"
   helmRepo:
     repoName: "registry1"
     chartName: "loki"
-    tag: "5.23.1-bb.2"
+    tag: "5.31.0-bb.0"
 
   # -- Flux reconciliation overrides specifically for the Loki Package
   flux: {}