ci: fix test logs on linux

[ningmingxiao]

call "nerdctl logs --untils " time is 16:03:19

2026-05-11T16:09:34.1135624Z 2026/05/11 16:03:19  binary is /usr/local/bin/nerdctl arg is [logs --until 60s testlogs001] 

but json logs time is 16:01:40.459948268Z

logs --until 60s testlogs001]*******content is:{"log":"+ echo foo\n","stream":"stderr","time":"2026-05-11T16:01:40.459948277Z"}
2026-05-11T16:09:34.1137555Z {"log":"+ echo bar\n","stream":"stderr","time":"2026-05-11T16:01:40.461456573Z"}
2026-05-11T16:09:34.1137691Z {"log":"foo\n","stream":"stdout","time":"2026-05-11T16:01:40.459948268Z"}

the root reason should be the number exceeds the maximum concurrent test case limit, and some test cases will be queued .
The default concurrency of t.Parallel() is the number of CPU cores.
so we can't run many testcase at a same time in test logs because it is Time-critical testcase.
fix #4889
@AkihiroSuda

[ningmingxiao]

After hundreds of tests, it works perfectly.

[ningmingxiao]

done thanks @sathiraumesh