Define Java version in one place in the container image

Signed-off-by: Jakub Scholz <www@scholzj.com>

Author: scholzj

docker-images/base/Dockerfile

@@ -21,7 +21,7 @@ RUN microdnf update -y \
     && microdnf reinstall -y tzdata \
     && microdnf clean all -y
 
-ENV JAVA_HOME=/usr/lib/jvm/jre-21
+ENV JAVA_HOME=/usr/lib/jvm/jre-${JAVA_VERSION}
 
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 # Add Tini