Task #10339: Use "latest" tag by default when deciding which CEP4 image to run

MAC/Services/src/PipelineControl.py

@@ -173,11 +173,11 @@ class Parset(dict):
 
   @staticmethod
   def defaultDockerImage():
-    return runCommand("docker-template", "lofar-pipeline:${LOFAR_TAG}")
+    return "lofar-pipeline:latest"
 
   @staticmethod
   def defaultDockerTag():
-    return runCommand("docker-template", "${LOFAR_TAG}")
+    return "latest"
 
   def dockerImage(self):
     # Return the version set in the parset, and fall back to our own version.