Using constant values instead of reassigning variables in each check …

…run (#17749)

* using const instead of reassigning vars in function

* adding changelog

windows_service/changelog.d/17749.fixed

@@ -0,0 +1 @@
+Using constant values instead of reassigning variables in each check run

windows_service/datadog_checks/windows_service/windows_service.py

@@ -115,6 +115,7 @@ class ServiceView(object):
     }
     STARTUP_TYPE_DELAYED_AUTO = "automatic_delayed_start"
     STARTUP_TYPE_UNKNOWN = "unknown"
+    DISPLAY_NAME_UNKNOWN = "Not_Found"
 
     def __init__(self, scm_handle, name):
         self.scm_handle = scm_handle
@@ -308,18 +309,16 @@ def check(self, instance):
             for service in services_unseen:
                 # if a name doesn't match anything (wrong name or no permission to access the service), report UNKNOWN
                 status = self.UNKNOWN
-                startup_type_string = ServiceView.STARTUP_TYPE_UNKNOWN
-                display_name = "Not_Found"
 
                 tags = ['windows_service:{}'.format(service)]
 
                 tags.extend(custom_tags)
 
                 if instance.get('windows_service_startup_type_tag', False):
-                    tags.append('windows_service_startup_type:{}'.format(startup_type_string))
+                    tags.append('windows_service_startup_type:{}'.format(ServiceView.STARTUP_TYPE_UNKNOWN))
 
                 if instance.get('collect_display_name_as_tag', False):
-                    tags.append('display_name:{}'.format(display_name))
+                    tags.append('display_name:{}'.format(ServiceView.DISPLAY_NAME_UNKNOWN))
 
                 if not instance.get('disable_legacy_service_tag', False):
                     self._log_deprecation('service_tag', 'windows_service')