gh-38148: Fix test failure on 32-bit where a different element is picked
On Debian 12 32-bit I get:
```
**********************************************************************
File "src/sage/geometry/polyhedral_complex.py", line 935, in
sage.geometry.polyhedral_complex.PolyhedralComplex._an_element_
Failed example:
pc._an_element_().vertices_list()
Expected:
[[0, 0], [0, 1/2], [1, 2]]
Got:
[[0, 0], [1/3, 1/3], [1, 2]]
**********************************************************************
1 item had failures:
1 of 4 in
sage.geometry.polyhedral_complex.PolyhedralComplex._an_element_
[469 tests, 1 failure, 17.41 s]
----------------------------------------------------------------------
sage -t --long --random-seed=0 src/sage/geometry/polyhedral_complex.py
# 1 doctest failed
----------------------------------------------------------------------
```
Just accept either of the two maximal cells
URL: https://github.com/sagemath/sage/pull/38148
Reported by: Volker Braun
Reviewer(s): Matthias Köppe
