{RDBMS} az postgres flexible-server create: Fix the comparator for so…

…rting sku name so it also sort the core number too when displaying the error message (#30582)

Co-authored-by: Matthew Boentoro <mboentoro@microsoft.com>

src/azure-cli/azure/cli/command_modules/rdbms/validators.py

@@ -453,13 +453,24 @@ def _pg_tier_validator(tier, sku_info):
 
 
 def compare_sku_names(sku_1, sku_2):
-    regex_pattern = r"_v(\d)"
+    regex_pattern = r"\D+(?P<core_number>\d+)\D+(?P<version>\d*)"
 
     sku_1_match = re.search(regex_pattern, sku_1)
     sku_2_match = re.search(regex_pattern, sku_2)
 
-    return (int(sku_2_match.group(1)) if sku_2_match else 0) - \
-        (int(sku_1_match.group(1)) if sku_1_match else 0)
+    # the case where version number is different, sort by the version number first
+    if sku_1_match.group('version') and int(sku_2_match.group('version')) > int(sku_1_match.group('version')):
+        return 1
+    if sku_1_match.group('version') and int(sku_2_match.group('version')) < int(sku_1_match.group('version')):
+        return -1
+
+    # the case where version number is the same, we want to sort by the core number
+    if int(sku_2_match.group('core_number')) > int(sku_1_match.group('core_number')):
+        return 1
+    if int(sku_2_match.group('core_number')) < int(sku_1_match.group('core_number')):
+        return -1
+
+    return 0
 
 
 def _pg_sku_name_validator(sku_name, sku_info, tier, instance):