update has_diagonalizing_gates and remove xfail on test

[lillian542]

Context:
A missing check in has_diagonalizing_gates was causing CompositeOp instances to sometimes incorrectly return True for has_diagonalizing_gates, i.e.:

>>> op1 = qml.PauliZ(0)
>>> op2 = qml.Rot(1.2, 2.3, 3.4, wires=0)
>>> op3 = qml.IsingZZ(4.32, wires=("a", "b"))
>>> op = qml.prod(op1, op2, op3)
>>> op.has_diagonalizing_gates    # should be False
True

Description of the Change:
Add the missing check to create consistency between for what base operators a CompositeOp can return diagonalizing_gates, and what for what operators it returns True for has_diagonalzing_gates.

Removes the xfail for the related test.

[github-actions]

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[lillian542]

[sc-49608]

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

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Additional details and impacted files

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