gh-157788: Fix test_long_task_name_is_truncated by not hardcoding main task name

[hugovk]

Fixes #157790 (comment).

The refleaks buildbots run with -R 3:3 so does 3 warmups and 3 runs, so the test is run 6 times in the same process. The first task name is "Task-1" for the first run, and "Task-4" for the second, and so on.

• Issue: python -m asyncio ps fails if any task name is longer than 255 characters #157788

[bedevere-bot]

🤖 New build scheduled with the buildbot fleet by @hugovk for commit 04d98a4 🤖

Results will be shown at:

https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F157911%2Fmerge

If you want to schedule another build, you need to add the 🔨 test-with-refleak-buildbots label again.

[bedevere-bot]

🤖 New build scheduled with the buildbot fleet by @hugovk for commit 04d98a4 🤖

Results will be shown at:

https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F157911%2Fmerge

If you want to schedule another build, you need to add the 🔨 test-with-refleak-buildbots label again.

[hugovk]

Passing so far on buildbots:

• https://buildbot.python.org/#/builders/1606/builds/965
• https://buildbot.python.org/#/builders/1562/builds/952
• https://buildbot.python.org/#/builders/1367/builds/1193

[encukou]

Thank you! It passes, I'll merge to unblock the buildbots.

I wonder if adding a name argument to run would be useful. For tests only it's definitely not worth it.

[miss-islington-app]

Thanks @hugovk for the PR 🌮🎉.. I'm working now to backport this PR to: 3.14, 3.15.
🐍🍒⛏🤖

[bedevere-app]

GH-157941 is a backport of this pull request to the 3.15 branch.

[bedevere-app]

GH-157942 is a backport of this pull request to the 3.14 branch.