Default the clientkey to the usual default

that is used everywhere else, for example in the default config of the
pipeline cli

Dockerfile

@@ -14,7 +14,7 @@ LABEL maintainer="DAISY Consortium (http://www.daisy.org/)"
 COPY --from=builder /usr/src/daisy-pipeline2/target/pipeline2-*_linux/daisy-pipeline /opt/daisy-pipeline2
 ENV PIPELINE2_LOCAL=false \
     PIPELINE2_AUTH=true \
-    PIPELINE2_AUTH_CLIENTKEY=clientkey \
+    PIPELINE2_AUTH_CLIENTKEY=clientid \
     PIPELINE2_AUTH_CLIENTSECRET=sekret
 EXPOSE 8181
 ENTRYPOINT ["/opt/daisy-pipeline2/bin/pipeline2"]