Incorrect Positioning of Fixed Orientation Mobjects in OpenGL

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Consider the following scene:

```python
class Test(ThreeDScene):
def construct(self):
self.camera.set_phi(TAU/6)
self.begin_ambient_camera_rotation(rate=0.5)
u = Vector(2*RIGHT, color = RED)
u_label = MathTex("1.0 \\vec u")
u_label.next_to(u.get_end(), RIGHT, buff = 0)
v = Vector(2*LEFT, color = YELLOW)
v_label = MathTex("1.0 \\vec v")
v_label.next_to(v.get_end(), LEFT, buff = 0)
self.add(u, v)
self.add_fixed_orientation_mobjects(u_label, v_label)
self.wait(TAU*2)
```

Here is the result of rendering with the opengl renderer:


As you can see, the label's position changes over time when it shouldn't. With cairo, the problem isn't there:


Start by running the provided ThreeDScene example with the OpenGL renderer and compare it with the Cairo result. Trace the handling of fixed-orientation mobjects during the ambient camera rotation; done means the u_label and v_label positions remain stable in OpenGL as they do with Cairo.

Written by the indexing model from the issue text.