[OPENJDK-777] singleton-jdk for ubi8/openjdk-8

In RHEL 8.6, prometheus-jmx-exporter depends upon
prometheus-jmx-exporter-jdk-binding, which is provided only by
prometheus-jmx-exporter-openjdk11, which pulls in OpenJDK 11.

Use singleton-jdk to clean up JDK11.

Signed-off-by: Jonathan Dowland <[email protected]>

Author: jmtd

ubi8-openjdk-8.yaml

@@ -50,6 +50,7 @@ modules:
     version: "8.2.3.6.8"
   - name: jboss.container.util.nss-wrapper
   - name: jboss.container.java.s2i.bash
+  - name: jboss.container.java.singleton-jdk
 
 help:
   add: true