CI/TST #34131 fixed test_floordiv_axis0_numexpr_path
xref #34131 

- [ x ] passes `black pandas`
- [ x ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`

Test `/pandas/tests/frame/test_floordiv_axis0_numexpr_path` is slow. It builds a df with 10^6 elements to tests functions `floordiv` and `pow`. The number of elements can be reduced with keeping the same min/max values inside the dataframe.

Before/after timeit comparison:
```
26.6 s ± 1.04 s per loop (mean ± std. dev. of 7 runs, 1 loop each)
37.6 ms ± 3.45 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)
```
I did it : green light :-D I had hard time with it !!!

Summary:
The tests are skipped if numexpr is not installed. Otherwise, the entry dataframe is built to construct the minimum of element to reduce the duration of the test. this is ok, ping on green. thanks @OlivierLuG 