[Bug]: pyplot.quiverkey does not work as expected with polar subplots

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### Bug summary

`pyplot.quiverkey` does not work correctly in polar plots.

### Code for reproduction

```python
import numpy as np
from matplotlib import pyplot as plt

fig, ax = plt.subplots(subplot_kw={"polar": True})

longitude = np.arange(0, 360, 10)
colatitude = 90 - np.ones_like(longitude) * 60

sample_x = np.ones_like(longitude) # Northward
sample_y = np.zeros_like(longitude) # Eastward

q = ax.quiver(np.radians(longitude), colatitude, sample_y, -sample_x, angles="xy")
ax.quiverkey(q, X=0, Y=0, U=5, label='5 units')
```

### Actual outcome


### Expected outcome

The quiverkey should be a single line rather than a cartwheel.

### Additional information

_No response_

### Operating system

macOS Ventura 13.5

### Matplotlib Version

3.7.1

### Matplotlib Backend

Installed osx event loop hook. MacOSX

### Python version

3.10.11

### Jupyter version

4.0.1

### Installation

conda

Start by running the provided Python reproduction with a polar subplot and inspect the pyplot.quiverkey path and related quiver-key handling. Compare the polar result with a non-polar plot; done means the polar quiver key renders as one line rather than a cartwheel while preserving the expected 5-unit label.

Written by the indexing model from the issue text.