Apply suggestions from code review

Author: haiqi96

components/clp-py-utils/clp_py_utils/s3_utils.py

@@ -205,14 +205,14 @@ def parse_s3_url(s3_url: str) -> Tuple[str, str, str]:
     """
 
     host_style_url_regex = re.compile(
-        r"https://(?P<bucket_name>[a-z0-9.-]+)\.s3(\.(?P<region_code>[a-z]+-[a-z]+-[0-9]))?"
+        r"https://(?P<bucket_name>[a-z0-9.-]+)\.s3(\.(?P<region_code>[a-z]+-[a-z]+-[0-9]))"
         r"\.(?P<endpoint>[a-z0-9.-]+)/(?P<key_prefix>[^?]+).*"
     )
     match = host_style_url_regex.match(s3_url)
 
     if match is None:
         path_style_url_regex = re.compile(
-            r"https://s3(\.(?P<region_code>[a-z]+-[a-z]+-[0-9]))?\.(?P<endpoint>[a-z0-9.-]+)/"
+            r"https://s3(\.(?P<region_code>[a-z]+-[a-z]+-[0-9]))\.(?P<endpoint>[a-z0-9.-]+)/"
             r"(?P<bucket_name>[a-z0-9.-]+)/(?P<key_prefix>[^?]+).*"
         )
         match = path_style_url_regex.match(s3_url)