gh-129363: Change regrtest sequential mode output

[vstinner]

First, write the test name without color. Then, write the test name and the result with color. Each test is displayed twice.

Example:

• Issue: python -m test color print with and without -j #129363

[vstinner]

cc @hugovk @Yhg1s

[hugovk]

This is an improvement but will double the length of the logs.

Shall we take inspiration from pytest, which first prints the (uncoloured) name of the test, and then appends the coloured result?

So we could do it something like this?

[vstinner]

Shall we take inspiration from pytest, which first prints the (uncoloured) name of the test, and then appends the coloured result?

Currently, when a test fails, it's output is written directly. So we cannot just add "passed" or "failed" after running a test.

Example (I added a bug to test_os):

0:00:00 load avg: 0.41 [1/1] test_os
test test_os failed -- Traceback (most recent call last):
  File "/home/vstinner/python/main/Lib/test/test_os.py", line 188, in test_access
    x
NameError: name 'x' is not defined

0:00:00 load avg: 0.41 [1/1/1] test_os failed (1 error)

[vstinner]

I wrote #129687 instead, I abandon this PR.