Fix deprecated Numpy logic in NormalizeRXAngles (#11023)

* Fix deprecated Numpy logic in `NormalizeRXAngles`

This new pass added in gh-10634 uses some deprecated Numpy properties
and has some slightly fragile exception-based logic when the required
properties can be directly tested.  This code issues warnings with Numpy
1.25+, which is currently not used by CI due to gh-10305.

* Fix return value

(cherry picked from commit 6bf90fa)

qiskit/transpiler/passes/optimization/normalize_rx_angle.py

@@ -76,25 +76,16 @@ def quantize_angles(self, qubit, original_angle):
             float: Quantized angle.
         """
 
-        # check if there is already a calibration for a simliar angle
-        try:
-            angles = self.already_generated[qubit]  # 1d ndarray of already generated angles
-            similar_angle = angles[
-                np.isclose(angles, original_angle, atol=self.resolution_in_radian / 2)
-            ]
-            quantized_angle = (
-                float(similar_angle[0]) if len(similar_angle) > 1 else float(similar_angle)
-            )
-        except KeyError:
-            quantized_angle = original_angle
-            self.already_generated[qubit] = np.array([quantized_angle])
-        except TypeError:
-            quantized_angle = original_angle
-            self.already_generated[qubit] = np.append(
-                self.already_generated[qubit], quantized_angle
-            )
-
-        return quantized_angle
+        if (angles := self.already_generated.get(qubit)) is None:
+            self.already_generated[qubit] = np.array([original_angle])
+            return original_angle
+        similar_angles = angles[
+            np.isclose(angles, original_angle, atol=self.resolution_in_radian / 2)
+        ]
+        if similar_angles.size == 0:
+            self.already_generated[qubit] = np.append(angles, original_angle)
+            return original_angle
+        return float(similar_angles[0])
 
     def run(self, dag):
         """Run the NormalizeRXAngle pass on ``dag``.