Add config to customize which image gets used for the connection test

Author: marcleblanc2

charts/sourcegraph/templates/tests/test-connection.yaml

@@ -10,7 +10,7 @@ metadata:
 spec:
   containers:
     - name: wget
-      image: busybox
+      image: {{ include "sourcegraph.image" (list . "sgTestConnection") }}
       command: ['wget']
       args: ['sourcegraph-frontend:30080/']
   restartPolicy: Never

charts/sourcegraph/values.yaml

@@ -1088,6 +1088,11 @@ sgTestConnection:
   # Run a connection test after instance startup, for CI/CD testing
   # Setting to true to not change default behaviour
   enabled: true
+  image:
+    # -- Docker image tag for the sg-test-connection pod
+    defaultTag: ''
+    # -- Docker image name for the sg-test-connection pod
+    name: "busybox"
 
 storageClass:
   # -- Enable creation of storageClass.