HADOOP-15711. Move branch-2 precommit/nightly test builds to java 8

(cherry picked from commit da675796017f79d88e58a3b931fb6358c7b63ff2)

dev-support/docker/Dockerfile

@@ -81,6 +81,15 @@ RUN apt-get -q update \
     && apt-get clean \
     && rm -rf /var/lib/apt/lists/*
 
+#######
+# OpenJDK 8
+#######
+# hadolint ignore=DL3008
+RUN apt-get -q update \
+    && apt-get -q install -y --no-install-recommends openjdk-8-jdk \
+    && apt-get clean \
+    && rm -rf /var/lib/apt/lists/*
+
 #######
 # OpenJDK 7
 #######
@@ -90,6 +99,7 @@ RUN apt-get -q update \
     && apt-get -q install -y --no-install-recommends openjdk-7-jdk \
     && apt-get clean \
     && rm -rf /var/lib/apt/lists/*
+RUN update-java-alternatives --set java-1.7.0-openjdk-amd64
 
 ######
 # Install cmake 3.1.0 (3.5.1 ships with Xenial)
@@ -203,7 +213,7 @@ RUN curl -L -s -S \
 ###
 # Avoid out of memory errors in builds
 ###
-ENV MAVEN_OPTS -Xms256m -Xmx1536m
+ENV MAVEN_OPTS -Xms256m -Xmx1536m -Dhttps.protocols=TLSv1.2
 
 
 ###