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

@@ -35,7 +35,10 @@ FROM build-image AS build-stage
 ARG REPONAME
 ARG BUILD_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
 
 WORKDIR /opt/${REPONAME}