fix(policy): update ConstraintIsolationLevel object

src/policy/src/main/java/eu/teraflow/policy/Serializer.java

...low/policy/context/model/ConstraintSlaIsolationLevel.java

.../src/test/java/eu/teraflow/policy/ConstraintTypeTest.java

...licy/src/test/java/eu/teraflow/policy/SerializerTest.java

...get/generated-sources/grpc/context/ContextOuterClass.java

src/policy/target/kubernetes/kubernetes.yml