`ConservativeVector`, `RootVector` and `RootHashMap` are final types,
and their base classes have a protected destructor, so when their
destructor is called, the static and dynamic types will be the same
(can't destruct them through a pointer to a base or derived class).
Therefore, there is no need for a virtual destructor.
This fixes the newly introduced `-Wunnecessary-virtual-specifier`
Clang warning (llvm/llvm-project#131188).
