NSHM Unit tests

When running NSHM unit tests in pipeline, instead of running the hazard calculation in the junit test itself the hazard calculation is done by running a java class and writing out the results to JSON files.

src/test/java/gov/usgs/earthquake/nshmp/model/NshmTestUtils.java

@@ -61,7 +61,7 @@ class NshmTestUtils {
     return new NshmModel(
         nshm,
         ModelLoader.load(nshm.modelPath()),
-        Executors.newFixedThreadPool(cores));
+        Executors.newFixedThreadPool(4));
   }
 
   /**