use update-java-alternatives to install JDK 11

Change-Id: Id90d219f381b0c59f5dc3234cb6fd5615c76dc1d
diff --git a/jjb/onos/install-jdk.sh b/jjb/onos/install-jdk.sh
index bbca982..ed22bf4 100644
--- a/jjb/onos/install-jdk.sh
+++ b/jjb/onos/install-jdk.sh
@@ -17,10 +17,7 @@
 if [ ${GERRIT_BRANCH} == "master" -o ${GERRIT_BRANCH} == "onos-2.2" ]
 then
     echo Installing OPEN JDK 11
-    curl -L -o jdk.tar.gz -s https://cdn.azul.com/zulu/bin/zulu11.31.11-ca-jdk11.0.3-linux_x64.tar.gz
-    tar xf jdk.tar.gz
-    export JAVA_HOME="$HOME/zulu11.31.11-ca-jdk11.0.3-linux_x64"
-    PATH="$JAVA_HOME/bin:$PATH"
+    sudo update-java-alternatives -s java-1.11.0-openjdk-amd64
     which java
 else
     echo Using default JDK