chore: format and optimize Dockerfiles (#256)

images/base/Dockerfile.ubuntu

@@ -1,17 +1,19 @@
 FROM ubuntu:22.04
 
 SHELL ["/bin/bash", "-c"]
+ENV DEBIAN_FRONTEND noninteractive
 
 # Install the Docker apt repository
 RUN apt-get update && \
-    DEBIAN_FRONTEND="noninteractive" apt-get upgrade --yes && \
-    DEBIAN_FRONTEND="noninteractive" apt-get install --yes ca-certificates
+    apt-get upgrade --yes && \
+    apt-get install --yes ca-certificates && \
+    rm -rf /var/lib/apt/lists/*
 COPY docker-archive-keyring.gpg /usr/share/keyrings/docker-archive-keyring.gpg
 COPY docker.list /etc/apt/sources.list.d/docker.list
 
 # Install baseline packages
 RUN apt-get update && \
-    DEBIAN_FRONTEND="noninteractive" apt-get install --yes \
+    apt-get install --yes \
     bash \
     build-essential \
     ca-certificates \
@@ -36,7 +38,8 @@ RUN apt-get update && \
     rsync && \
     # Install latest Git using their official PPA
     add-apt-repository ppa:git-core/ppa && \
-    DEBIAN_FRONTEND="noninteractive" apt-get install --yes git
+    apt-get install --yes git \
+    && rm -rf /var/lib/apt/lists/*
 
 # Enables Docker starting with systemd
 RUN systemctl enable docker

images/base/mirrorlist

@@ -1 +0,0 @@
-Server=https://archive.archlinux.org/repos/2021/02/01/$repo/os/$arch

images/minimal/Dockerfile.ubuntu

@@ -8,10 +8,8 @@ RUN apt-get update && \
     ca-certificates \
     curl \
     git \
-	sudo
-
-RUN apt-get clean && \
-    rm -rf /var/lib/apt/lists/*
+    sudo \
+    && rm -rf /var/lib/apt/lists/*
 
 RUN useradd coder \
     --create-home \