Try running CI against Zulu (#36391)

This commit adds Zulu to the CI rotation. This commit only means that we
are going to try running CI against Zulu, it does not carry any
implications of support in the past, now, or in the future.

Author: jasontedor

.ci/matrix-runtime-javas.yml

@@ -9,3 +9,5 @@ ES_RUNTIME_JAVA:
   - java8
   - java8fips
   - java11
+  - zulu8
+  - zulu11