(maint) Switch PDB container off of Alpine

 - Alpine seems to still be having issues with DNS resolutions inside
   an LCOW environment. In an effort to reduce these transient
   problems, switch the base container to a non-Alpine platform.

   A ticket has been filed with a repro at :

   moby/libnetwork#2371

 - While this may increase the image size a bit, the goal here is
   reliability and robustness

 - Ubuntu 18.04 shares a lineage with debian buster, which should
   be a well supported platform for PDB

docker/puppetdb/Dockerfile

@@ -1,4 +1,4 @@
-FROM clojure:lein-alpine AS builder
+FROM clojure:openjdk-8-lein AS builder
 RUN apk add --no-cache make
 # Install only dependencies
 WORKDIR /app
@@ -11,7 +11,7 @@ COPY . /app
 RUN lein with-profile uberjar uberjar
 
 
-FROM openjdk:8-jre-alpine
+FROM openjdk:8-jre-stretch
 RUN apk add --no-cache tini curl openssl bind-tools
 COPY --from=builder /app/target/puppetdb.jar /