refact(fock/pure): Simplify fock_probabilities

Previously when calculating the particle number detection probabilities
the length of the state vector was calculated and used to slice the
result for unknown reason. This is unnecesarry because the result has
already the desired length, so this has been deleted.

piquasso/_backends/fock/pure/state.py

@@ -117,11 +117,7 @@ def get_particle_detection_probability(
 
     @property
     def fock_probabilities(self) -> np.ndarray:
-        cardinality = cutoff_cardinality(d=self._space.d, cutoff=self._config.cutoff)
-
-        return self._np.real((self._state_vector * self._np.conj(self._state_vector)))[
-            :cardinality
-        ]
+        return self._np.real((self._state_vector * self._np.conj(self._state_vector)))
 
     @property
     def fock_probabilities_map(self) -> Dict[Tuple[int, ...], float]: