Only make tidal mixing files for meshes with cavities

Since the tidal model used to produce the dataset only covers the
Southern Ocean, there is not much value in having the reampped
dataset for meshes without cavities.  If we want to make a more
general mixing parameterization that uses tidal information, we
would need to use data from a global tidal model for the input
dataset in the future.

compass/ocean/tests/global_ocean/files_for_e3sm/remap_tidal_mixing.py

@@ -34,13 +34,22 @@ def __init__(self, test_case):
             target='ustar_CATS2008_S71W70.nc',
             database='tidal_mixing')
 
-        self.add_output_file(filename='velocityTidalRMS_CATS2008.nc')
+    def setup(self):
+        """
+        setup input and output files based on config options
+        """
+        super().setup()
+        if self.with_ice_shelf_cavities:
+            self.add_output_file(filename='velocityTidalRMS_CATS2008.nc')
 
     def run(self):
         """
         Run this step of the test case
         """
         super().run()
+        if not self.with_ice_shelf_cavities:
+            return
+
         logger = self.logger
         config = self.config
         ntasks = self.ntasks