NAT-328: updated validation site name by an utils method

gso/workflows/site/create_site.py

 import ipaddress
-import re
 from typing import NoReturn
 
 import pycountry
@@ -15,6 +14,7 @@ from gso.products.product_blocks import site as site_pb
 from gso.products.product_blocks.site import LatitudeCoordinate, LongitudeCoordinate
 from gso.products.product_types import site
 from gso.services.crm import customer_selector
+from gso.util.helpers import validate_site_name
 
 
 def initial_input_form_generator(product_name: str) -> FormGenerator:  # noqa: C901
@@ -52,12 +52,7 @@ def initial_input_form_generator(product_name: str) -> FormGenerator:  # noqa: C
 
         @validator("site_name", allow_reuse=True)
         def site_name_must_be_valid(cls, site_name: str) -> str | NoReturn:
-            # Accept 3 chapital letters and only one ditigt after capital letters.
-            pattern = re.compile(r"^[A-Z]{3}[0-9]?$")
-            if not bool(pattern.match(site_name)):
-                raise ValueError(f"Enter a valid site name similar looks like AMS, AMS1or LON9. Get: {site_name}")
-
-            return site_name
+            return validate_site_name(site_name)
 
     user_input = yield CreateSiteForm