CI: don't install jdk 11 for java8 build

We were installing jdk from the debian repos before installing jdk8 from
upstream. This caused java 11 to be used instead of java 8.

scripts/debian10/java8.pEpJNIAdapter.debian10.Dockerfile

@@ -23,12 +23,6 @@ WORKDIR ${BUILDROOT}/libpEpAdapter
 RUN sh ./scripts/${CURRENT_DISTRO}/build_libpEpAdapter.sh && \
     rm -rf ${BUILDROOT}/*
 
-### Install system dependencies
-USER root
-RUN apt-get update -yqq && \
-    apt-get install -yqq default-jdk-headless
-USER pep-builder
-
 
 ## Build and install pEpJNIAdapter
 ### Install Java 8