[Attributor][FIX] Avoid double free (and useless state copy)

In an attempt to remove the memory leak we introduced a double free.
The problem was that we allowed a plain copy of the state and it was
actually used. The use was useless, so it is gone now. The copy
constructor is gone as well. The move constructor ensures the Accesses
pointers are owned by a single state, I hope.

Reported by: https://lab.llvm.org/buildbot/#/builders/16/builds/25820