dws: improve error message

Problem: the error message for requesting too much lustre storage
gives a float, but an integer would be better and more consistent
with the other file system types.

Provide an integer in the error message by doing integer division
instead of normal float division.

src/python/flux_k8s/directivebreakdown.py

@@ -46,7 +46,7 @@ def validate(self, nodecount):
             requested = getattr(self, attr)
             allowable = getattr(type(self), attr)
             if attr == "lustre":
-                requested = requested / nodecount
+                requested = requested // nodecount
             if allowable is not None and requested > allowable:
                 raise ValueError(
                     f"Requested a total of {requested} GiB of {attr} storage "