Fixes#24624
This seems to have been broken in
https://github.com/go-gitea/gitea/pull/21563
Previously, this code read
```
// Are we looking at default webhooks?
if ctx.Params(":configType") == "default-hooks" {
return &orgRepoCtx{
IsAdmin: true,
Link: path.Join(setting.AppSubURL, "/admin/hooks"),
LinkNew: path.Join(setting.AppSubURL, "/admin/default-hooks"),
NewTemplate: tplAdminHookNew,
}, nil
}
// Must be system webhooks instead
return &orgRepoCtx{
IsAdmin: true,
IsSystemWebhook: true,
Link: path.Join(setting.AppSubURL, "/admin/hooks"),
LinkNew: path.Join(setting.AppSubURL, "/admin/system-hooks"),
NewTemplate: tplAdminHookNew,
}, nil
```
but was simplified to
```
return &ownerRepoCtx{
IsAdmin: true,
IsSystemWebhook: ctx.Params(":configType") == "system-hooks",
Link: path.Join(setting.AppSubURL, "/admin/hooks"),
LinkNew: path.Join(setting.AppSubURL, "/admin/system-hooks"),
NewTemplate: tplAdminHookNew,
}, nil
```
In other words, combining the `IsSystemWebhook` check into a one-liner
and forgetting that `LinkNew` also depended on it. This meant the
rendered `<form>` always POSTed to `/admin/system-hooks`, even when you
had GETed `/admin/default-hooks/gitea/new`.