Drop CentOS 5 from launch script tests and upgrade to 6.9

CentOS 5 was declared EOL in March 2017 and yum on longer works
out of the box. 6.9 is the latest release of CentOS 6. Tests for
CentOS 7 have not been added as it uses systemd rather than SysVinit.

Closes gh-9395

spring-boot-integration-tests/spring-boot-launch-script-tests/src/test/resources/conf/CentOS/5.11-7f8a8084/Dockerfile

-# CentOS 5.11 from 22/03/2016
-FROM centos@sha256:7f8a808416f712da6931ac65e4308fede7fe86bcf15364b6f63af88840fe6131
-RUN yum install -y wget && \
-    yum install -y system-config-services && \
-    yum install -y curl && \
-    wget --no-cookies \
-        --no-check-certificate \
-        --header  "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; oraclelicense=accept-securebackup-cookie" \
-        --output-document jdk.rpm \
-        http://download.oracle.com/otn-pub/java/jdk/8u66-b17/jdk-8u66-linux-x64.rpm && \
-    yum --nogpg localinstall -y jdk.rpm && \
-    rm -f jdk.rpm

spring-boot-integration-tests/spring-boot-launch-script-tests/src/test/resources/conf/CentOS/6.7-4f6d8f79/Dockerfile

-# CentOS 6.7 from 22/03/2016
-FROM centos@sha256:4f6d8f794af3574eca603b965fc0b63fdf852be29c17d3ab4cad7ec2272b82bd
-RUN yum install -y wget && \
-    yum install -y system-config-services && \
-    yum install -y curl && \
-    wget --no-cookies \
-        --no-check-certificate \
-        --header  "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; oraclelicense=accept-securebackup-cookie" \
-        --output-document jdk.rpm \
-        http://download.oracle.com/otn-pub/java/jdk/8u66-b17/jdk-8u66-linux-x64.rpm && \
-    yum --nogpg localinstall -y jdk.rpm && \
-    rm -f jdk.rpm

spring-boot-integration-tests/spring-boot-launch-script-tests/src/test/resources/conf/CentOS/6.9-a23bced6/Dockerfile

+# CentOS 6.9 from 02/06/2017
+FROM centos@sha256:a23bced61701af9a0a758e94229676d9f09996a3ff0f3d26955b06bac8c282e0
+RUN yum install -y wget && \
+    yum install -y system-config-services && \
+    yum install -y curl && \
+    wget --output-document jdk.rpm \
+        http://cdn.azul.com/zulu/bin/zulu8.21.0.1-jdk8.0.131-linux.x86_64.rpm && \
+    yum --nogpg localinstall -y jdk.rpm && \
+    rm -f jdk.rpm