fix: pin busybox image digest and add pull policy for init container

Author: wrn14897

charts/hdx-oss-v2/templates/hyperdx-deployment.yaml

@@ -50,7 +50,8 @@ spec:
       {{- if .Values.mongodb.enabled }}
       initContainers:
         - name: wait-for-mongodb
-          image: busybox
+          image: "busybox@sha256:1fcf5df59121b92d61e066df1788e8df0cc35623f5d62d9679a41e163b6a0cdb"
+          imagePullPolicy: IfNotPresent
           command: ['sh', '-c', 'until nc -z {{ include "hdx-oss.fullname" . }}-mongodb {{ .Values.mongodb.port }}; do echo waiting for mongodb; sleep 2; done;']
       {{- end }}
       containers: