[BUG] Update `qml.draw()` across demos.

[josh146]

In the latest version of PennyLane, qml.draw() defaults to drawing the QNode as is, without expanding templates.

However, some of the demos (including tutorial_qaoa_intro.py) use the circuit drawer to show how templates are expanded on devices.

Where applicable, demos should be updated to use qml.draw(qnode, expansion_strategy="device") if it is required. Note that demos that draw circuits without templates likely don't need this change.