Mesos allocator leaks role sorter and quota role sorters.

The Mesos allocator internal::HierarchicalAllocatorProcess owns two raw pointer members roleSorter and quotaRoleSorter, but fails to properly manage their lifetime; they are e.g., not cleaned up in the allocator process destructor.

Since currently we do not recreate an existing allocator in production code they seem to be unaffected by these leaks; they do affect tests though where we create allocators multiple times.