Remove (unused/duplicated) OpenJDK from Docker image (#2318)

The Docker image installs `maven` via `apt` which _also_ installs Java
(if required), defaulting to OpenJDK.

We then subsequently install Eclipse Temurin JDK - rendering OpenJDK
redundant, taking up space.

If we re-order the steps, OpenJDK will never be installed.

Author: JackPGreen

Dockerfile

@@ -8,7 +8,6 @@ RUN apt-get update && apt-get install -y software-properties-common \
     && add-apt-repository ppa:deadsnakes/ppa \
     && apt-get update && apt-get install -y \
         wget \
-        maven \
         python${PYTHON_VERSION} \
         python${PYTHON_VERSION}-distutils \
         python3-pip \
@@ -42,6 +41,9 @@ RUN JAVA_HOME_PATH=$(find /usr/lib/jvm -name "temurin-17*" -type d | head -1) &&
     echo "export JAVA_HOME=$JAVA_HOME_PATH" >> /etc/environment && \
     echo "export JAVA_HOME=$JAVA_HOME_PATH" >> /etc/bash.bashrc
 
+# Install Maven after JDK has been installed to avoid default JDK installation
+RUN apt-get update && apt-get install -y maven && rm -rf /var/lib/apt/lists/*
+
 # Install Terraform
 RUN curl -fsSL https://apt.releases.hashicorp.com/gpg | gpg --dearmor -o /usr/share/keyrings/hashicorp-archive-keyring.gpg && \
     echo "deb [signed-by=/usr/share/keyrings/hashicorp-archive-keyring.gpg] https://apt.releases.hashicorp.com $(lsb_release -cs) main" | tee /etc/apt/sources.list.d/hashicorp.list && \