upload: be more cautious about grabbing files for upload

Instead of looking for study name in the file, try harder to make sure
we are looking at a study *prefix* in the filename.

cumulus_library/actions/uploader.py

@@ -71,7 +71,7 @@ def upload_files(args: dict):
     if args["target"]:
         filtered_paths = []
         for path in file_paths:
-            if any(study in str(path) for study in args["target"]):
+            if any(f"/{study}__" in str(path) for study in args["target"]):
                 filtered_paths.append(path)
         file_paths = filtered_paths