Change golang and alpine image registry in Dockerfile

Signed-off-by: Shreyas Rao <[email protected]>

Dockerfile

@@ -1,5 +1,5 @@
 # Build the manager binary
-FROM golang:1.13.9 as builder
+FROM eu.gcr.io/gardener-project/3rd/library-1.docker.io/library/golang:1.13.9 as builder
 WORKDIR /go/src/github.com/gardener/etcd-druid
 COPY . .
 
@@ -12,7 +12,7 @@ RUN .ci/build
 
 # Use distroless as minimal base image to package the manager binary
 # Refer to https://github.com/GoogleContainerTools/distroless for more details
-FROM alpine:3.10.3 AS druid
+FROM eu.gcr.io/gardener-project/3rd/alpine:3.10.3 AS druid
 RUN apk add --update bash curl
 WORKDIR /
 COPY --from=builder /go/src/github.com/gardener/etcd-druid/bin/linux-amd64/etcd-druid bin/.