PMM-7 revert dockerfile changes.

Dockerfile

@@ -1,18 +1,9 @@
 FROM alpine AS builder
 RUN apk add --no-cache ca-certificates
 
-FROM golang:alpine as builder2
-
-RUN apk update && apk add make
-RUN mkdir /source
-COPY . /source
-WORKDIR /source
-RUN make init
-RUN make build
-
-FROM alpine AS final
+FROM scratch AS final
 USER 65535:65535
-COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
-COPY --from=builder2 /source/mongodb_exporter /
+COPY  --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
+COPY ./mongodb_exporter /
 EXPOSE 9216
 ENTRYPOINT ["/mongodb_exporter"]