Perf: Implement RAII for Mutex in RandomCIDFactory

[athy125]

Used RAII to manage the mutex in the RandomCIDFactory class. Replaced manual locking and unlocking with std::lock_guard for automatic locking and unlocking of the mutex within the critical sections of code

[bnoordhuis]

Misleading description: we're already using RAII, just not std::lock_guard

Technical: I strongly doubt this compiles because node::Mutex doesn't implement .lock() and .unlock()

Philosophical: either replace Mutex and ScopedLock wholesale across the code base with their std:: counterparts, or don't, but no halfsies

[athy125]

Understood, so basically if we're going to replace Mutex and ScopedLock with their std::counterparts, we'll need to make changes consistently throughout the code, yes?
For example Replace ScopedLock with std::unique_lock so on and so forth?

[bnoordhuis]

Yes, exactly.