daemon: Accept 'repeat' setting from untrusted users

Fixes #5352.

src/libstore/daemon.cc

@@ -235,6 +235,7 @@ struct ClientSettings
                 }
                 else if (trusted
                     || name == settings.buildTimeout.name
+                    || name == settings.buildRepeat.name
                     || name == "connect-timeout"
                     || (name == "builders" && value == ""))
                     settings.set(name, value);