fix(tests): disable JVM container support for opensearch 2.1.0

Works around a JDK cgroup v2 NPE in ProcessProbe <clinit> that crashes
opensearch 2.1.0 on GitHub runners using cgroup v2.

Author: chrisburr

tests/CI/envs/opensearchproject/opensearch:2.1.0.env

@@ -6,4 +6,6 @@ cluster.routing.allocation.disk.watermark.high=300mb
 plugins.security.disabled=true
 # Elasticsearch allocates 1GB of memory by default. As resources are limited
 # and elasticsearch performance isn't critical in CI, limit this to 256MB
-OPENSEARCH_JAVA_OPTS="-Xms256m -Xmx256m" # minimum and maximum Java heap size
+# -XX:-UseContainerSupport works around a JDK cgroup v2 NPE in OpenSearch 2.1.0
+# (ProcessProbe <clinit> crashes on newer GitHub runners with cgroup v2)
+OPENSEARCH_JAVA_OPTS="-Xms256m -Xmx256m -XX:-UseContainerSupport"