set up dask client test fix and add epic to nightly builds (#502)

Category: bugfix
JIRA issue: hotfix

When we run pytest --runslow, there are tests that run dask and set up a client which persists in the next tests. We were making an assumption that there is no dask client in test_set_up_dask_client_default. This PR shuts down a client if one already exists.
Add full scale testing epic to nightly builds.

Testing
Ran pytest --runslow.

Author: hussain-jafari

tests/unit/test_interface.py

@@ -104,10 +104,16 @@ def test_validate_source_compatibility_wrong_directory(tmp_path: Path) -> None:
 
 
 def test_set_up_dask_client_default() -> None:
-
-    # There should be no dask client yet
-    with pytest.raises(ValueError):
+    # Shut down a client if it exists
+    try:
         client = get_client()
+        client.shutdown()
+    except ValueError:
+        pass
+    finally:
+        # There should be no dask client at this point
+        with pytest.raises(ValueError):
+            client = get_client()
 
     set_up_dask_client()
     client = get_client()