Fix detection of ssm connection bucket region (#1428)

Fix detection of ssm connection bucket region

Fix detection of ssm connection bucket region by ensuring that the boto client is created normally and able to use supported credential sources
SUMMARY
PR #1176 introduced detection of an S3 bucket's region to handle cases where the bucket is in a different region than the SSM connection itself. This change did not use the preferred mechanism for creating client objects, which caused it to not have access to credentials from all supported sources. It also broke the ability to use this plugin in partitions other than aws. (e.g. aws-us-gov).
This change fixes this by building the bucket location client using _get_boto_client and the region for the connection to ensure it is both getting the proper credentials and starting in a region from the same partition as the client itself. From the default global region (or a hard-coded region), it will detect the bucket's region and continue S3 API calls using the bucket's own region.
Fixes bug introduced from #1176
Fixes #1413
ISSUE TYPE

Bugfix Pull Request

COMPONENT NAME
aws_ssm connection plugin

Reviewed-by: Markus Bergholz <git@osuv.de>
Reviewed-by: Alina Buzachis <None>
Reviewed-by: Mark Chappell <None>

Author: phene

changelogs/fragments/1428-aws-ssm-missing-credentials.yml

@@ -0,0 +1,2 @@
+bugfixes:
+  - aws_ssm - fixes S3 bucket region detection by ensuring boto client has correct credentials and exists in correct partition (https://github.com/ansible-collections/community.aws/pull/1428).

plugins/connection/aws_ssm.py

@@ -534,12 +534,14 @@ def _flush_stderr(self, subprocess):
     def _get_url(self, client_method, bucket_name, out_path, http_method, profile_name, extra_args=None):
         ''' Generate URL for get_object / put_object '''
 
-        bucket_location = boto3.client('s3').get_bucket_location(
+        region_name = self.get_option('region') or 'us-east-1'
+
+        bucket_location = self._get_boto_client('s3', region_name=region_name, profile_name=profile_name).get_bucket_location(
             Bucket=(self.get_option('bucket_name')),
         )
-        region_name = bucket_location['LocationConstraint']
+        bucket_region_name = bucket_location['LocationConstraint']
 
-        client = self._get_boto_client('s3', region_name=region_name, profile_name=profile_name)
+        client = self._get_boto_client('s3', region_name=bucket_region_name, profile_name=profile_name)
         params = {'Bucket': bucket_name, 'Key': out_path}
         if extra_args is not None:
             params.update(extra_args)