Refactor: Extract VLAN 1 pattern to module-level constant

Co-authored-by: qkalsky <234014210+qkalsky@users.noreply.github.com>

Author: Copilot

cloudshell/networking/cisco/command_actions/iface_actions.py

@@ -12,6 +12,9 @@
     iface,
 )
 
+# Pattern to match VLAN 1 configuration (default state that should be preserved)
+VLAN_1_PATTERN = r"^\s*switchport\s+trunk\s+allowed\s+vlan\s+1\s*$"
+
 
 class IFaceActions:
     def __init__(self, cli_service, logger):
@@ -115,11 +118,7 @@ def clean_interface_switchport_config(
         for line in current_config.splitlines():
             if line.strip(" ").startswith("switchport "):
                 # Skip removing "switchport trunk allowed vlan 1" as it's the default state
-                if re.match(
-                    r"^\s*switchport\s+trunk\s+allowed\s+vlan\s+1\s*$",
-                    line,
-                    re.IGNORECASE,
-                ):
+                if re.match(VLAN_1_PATTERN, line, re.IGNORECASE):
                     continue
                 line_to_remove = re.sub(r"\s+\d+[-\d+,]+", "", line).strip(" ")
                 CommandTemplateExecutor(