`Infinity` and `NaN` should be converted to `undefined` in JSON? Or base64 could/should be used to describe these values in the figure?

In #4470, the test_fast_track_finite_arrays, but it raised concerns that the replacement of NaN or Infinity with null in arrays is no longer running because the array is base64 encoded already when that code is run. The code that does the replacement currently is here

从 packages/python/plotly/plotly/tests/test_optional/test_utils/test_utils.py 开始，重点查看 test_fast_track_finite_arrays，并跟踪 packages/python/plotly/_plotly_utils/utils.py 中的替换逻辑。确定非有限值是在 base64 编码之前还是之后遇到的，然后确定预期表示形式，并添加测试覆盖以证明所选择的行为得以保留。