fix(java17): add options for java11 image variants (#2086)

Author: mattgogerly

halyard-config/src/main/java/com/netflix/spinnaker/halyard/config/model/v1/node/DeploymentEnvironment.java

@@ -95,7 +95,9 @@ public enum ImageVariant {
     SLIM("Based on an Alpine image"),
     UBUNTU("Based on Canonical's ubuntu:bionic image"),
     JAVA8("A variant of SLIM that uses the Java 8 runtime"),
-    UBUNTU_JAVA8("A variant of UBUNTU that uses the Java 8 runtime");
+    UBUNTU_JAVA8("A variant of UBUNTU that uses the Java 8 runtime"),
+    JAVA11("A variant of SLIM that uses the Java 11 runtime"),
+    UBUNTU_JAVA11("A variant of UBUNTU that uses the Java 11 runtime");
 
     @Getter final String description;