Fix domain isolation for the case when multiple domain type is involved

Previously when we were stacking domains we inserted the new domain
instructions between the upper most domain and its operand. This caused
issues if that domain had more then one user with different atribute for
the domain inserted at the second pass because we could have ended up
with edges between different domains.

After this change we insert the new domains between the lower most
domain and its user ensuring that the domain separates every instruction
with different attributes.

PiperOrigin-RevId: 209776741