Refactor CSRF protector (#32057) (#32069)

#32057 improves the CSRF handling and is worth to backport

routers/web/web.go

@@ -129,6 +129,8 @@ func webAuth(authMethod auth_service.Method) func(*context.Context) {
 			// ensure the session uid is deleted
 			_ = ctx.Session.Delete("uid")
 		}
+
+		ctx.Csrf.PrepareForSessionUser(ctx)
 	}
 }