ioc: use non-interactive install for build-stage.

This is required to use BUILD_PACKAGES to install any package. No
recommended package option has also been enabled to avoid unused
packages in the resulting IOC image. Lines have been broken to make it
easier to read and maintain this step.

Dockerfile

@@ -42,7 +42,10 @@ ARG REPONAME
 ARG BUILD_PACKAGES
 ARG BUILD_TAR_PACKAGES
 
-RUN if [ -n "$BUILD_PACKAGES" ]; then apt update && apt install $BUILD_PACKAGES; fi
+RUN if [ -n "$BUILD_PACKAGES" ]; then \
+        apt update && \
+        apt install -y --no-install-recommends $BUILD_PACKAGES; \
+    fi
 RUN lnls-get-n-unpack -r $BUILD_TAR_PACKAGES
 
 WORKDIR /opt/${REPONAME}