[BUG] annotate_sphere radius depends on choice of center

[cphyc]

Bug report

Bug summary

When annotating plots with a sphere, the apparent size of the sphere depends on the units of the center of the plot.

Code for reproduction

import yt
import numpy as np

ds = yt.load_sample("output_00080")

rad = ds.quan(200, "kpccm/h")
# Option 1
center = ds.arr(ds.all_data().argmax("density"))
# Option 2
center = ds.arr(ds.all_data().argmax("density")).in_units("code_length")
# Option 3
center = ds.arr(ds.all_data().argmax("density")).in_units("Mpccm/h")
sp = ds.sphere(center, 2*rad)

p = yt.ProjectionPlot(
    ds,
    "x",
    ("gas", "density"),
    center=center,
    width=rad * 2,
    data_source=sp,
    origin="native",
)
p.annotate_sphere(center, rad, circle_args={"color": "white"})
p.set_axes_unit("Mpccm/h")
p.save("/tmp/")

Actual outcome

Option	Outcome
1
2
3

Expected outcome

All three images should be the same.

[neutrinoceros]

It looks exactly as if input units are completely ignored and code units are assumed in all cases.

[cphyc]

Found the issue!