Revert "fix(api): document is_system_webhook field (#7784)" (#8286)

The field is not part of the struct, it is instead part of the config field. See https://codeberg.org/forgejo/forgejo/pulls/7784#issuecomment-5511212

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/8286
Reviewed-by: Beowulf <beowulf@beocode.eu>
Co-authored-by: Gusted <postmaster@gusted.xyz>
Co-committed-by: Gusted <postmaster@gusted.xyz>
(cherry picked from commit 507a12bf82)

modules/structs/hook.go

@@ -53,8 +53,7 @@ type CreateHookOption struct {
 	BranchFilter        string                 `json:"branch_filter" binding:"GlobPattern"`
 	AuthorizationHeader string                 `json:"authorization_header"`
 	// default: false
-	Active          bool `json:"active"`
-	IsSystemWebhook bool `json:"is_system_webhook"`
+	Active bool `json:"active"`
 }
 
 // EditHookOption options when modify one hook

templates/swagger/v1_json.tmpl

@@ -22178,10 +22178,6 @@
           },
           "x-go-name": "Events"
         },
-        "is_system_webhook": {
-          "type": "boolean",
-          "x-go-name": "IsSystemWebhook"
-        },
         "type": {
           "type": "string",
           "enum": [