Fix handling of statevector simulator detection

This commit fixes an oversight from an earlier development version that
slipped through later revisions where the statevector simulator backend
detection in the QuantumInstance class was hard coded to False for
BackendV2. This was just meant as a temporary debugging step while
getting the initial commit ready, but was never updated to remove this
until now.

qiskit/utils/quantum_instance.py

@@ -981,9 +981,7 @@ def backend_name(self):
     @property
     def is_statevector(self):
         """Return True if backend is a statevector-type simulator."""
-        if self._backend_interface_version <= 1:
-            return is_statevector_backend(self._backend)
-        return False
+        return is_statevector_backend(self._backend)
 
     @property
     def is_simulator(self):