[Develop] Fix retrieve_supported_regions to get the correct S3 Url (#6380)

* Fix retrieve_supported_regions to get the correct url

Author: hehe7318

CHANGELOG.md

@@ -13,6 +13,7 @@ CHANGELOG
 **BUG FIXES**
 - Fix validator `EfaPlacementGroupValidator` so that it does not suggest to configure a Placement Group when Capacity Blocks are used.
 - Fix sporadic cluster creation failures with managed FSx for Lustre.
+- Fix `retrieve_supported_regions` so that it can get the correct S3 url.
 
 3.10.1
 ------

cli/src/pcluster/utils.py

@@ -570,7 +570,7 @@ def retrieve_supported_regions():
         try:
             url = "https://{region}-aws-parallelcluster.s3.{region}.{aws_domain}/supported-regions".format(
                 region=region,
-                aws_domain=get_partition(region),
+                aws_domain=get_url_domain_suffix(region),
             )
             with urllib.request.urlopen(url) as f:  # nosec B310 nosemgrep
                 retrieve_supported_regions.cache = f.read().decode("utf-8").split("\n")