chore(release): Use the alpine containers instead of openjdk (spinnak…

…er#3343)

The container we had been using hasn't been updated in months. See
spinnaker/spinnaker#5204.

Dockerfile.slim

@@ -1,7 +1,7 @@
-FROM openjdk:8-jre-alpine
+FROM alpine:3.10
 MAINTAINER [email protected]
 COPY --from=compile /compiled_sources/orca-web/build/install/orca /opt/orca
-RUN apk --no-cache add --update bash
+RUN apk --no-cache add --update bash openjdk8-jre
 RUN adduser -D -S spinnaker
 USER spinnaker
 CMD ["/opt/orca/bin/orca"]