Update description for BucketAlreadyOwnedByYou err

Updated the error description for the CreateBucket operation when the
bucket is already owned by the user. The new message is compliant with
AWS error description.

Issue: ARSN-451

lib/errors/arsenalErrors.ts

@@ -42,7 +42,7 @@ export const BucketAlreadyOwnedByYou: ErrorFormat = {
     code: 409,
 
     description:
-        'A bucket with this name exists and is already owned by you',
+        'Your previous request to create the named bucket succeeded and you already own it.',
 };
 
 export const BucketNotEmpty: ErrorFormat = {