> scripted-diff: rename m_cs_callbacks_pending -> m_callbacks_mutex
> refactor: replace RecursiveMutex `m_callbacks_mutex` with Mutex
>
> In each of the critical sections, only the the guarded variables are
> accessed, without any chance that within one section another one is
> called. Hence, we can use an ordinary Mutex instead of RecursiveMutex.
This is a backport of core#24069