go: runtime: TestCgoPprofCallback hang on linux-arm

The mayMoreStackPreempt ones are #54885, which is fixed.

All the linux-amd64-longtest and linux-386-longtest failures are build with -dmaymorestack=mayMoreStackPreempt. They also haven’t happened for some time.

All the other failures appear to be on slow machines. This is a CPU intensive test: it calls runtime.GOMAXPROCS(16) and then starts 64 goroutines. Each goroutine does an endless loop of sleeping for 50 microseconds and calling a Go function. The program keeps this up for a full second. And, the test is run in parallel with other tests.

So I think this is a flaky test. I think we should not return this CPU intensive test in parallel with other tests, and since it takes a full second I think we should not run it in short mode.

CC @prattmic for other opinions since he wrote the test.

greplogs --dashboard -md -l -e 'CgoPprofCallback'

2022-09-06T11:14:09-1c50484/linux-amd64-longtest 2022-09-05T21:39:28-4c1ca42/linux-amd64-longtest 2022-09-05T08:28:34-bd5595d/linux-386-longtest 2022-09-05T08:12:37-67e6542/linux-amd64-longtest 2022-09-05T08:07:47-357b922/linux-amd64-longtest 2022-09-04T04:17:04-535fe2b/linux-amd64-longtest 2022-09-03T18:21:45-a0f0582/linux-386-longtest 2022-09-03T18:21:45-a0f0582/linux-amd64-longtest 2022-09-03T15:45:36-f798dc6/linux-amd64-longtest 2022-09-02T20:14:40-3e11e61/linux-amd64-longtest 2022-09-02T20:14:16-646c3ee/linux-amd64-longtest 2022-09-02T19:40:34-9154d4a/linux-amd64-longtest 2022-09-02T19:38:45-e406112/linux-amd64-longtest 2022-09-02T19:22:26-0fda8b1/linux-386-longtest 2022-09-02T19:08:56-b91e373/linux-amd64-longtest 2022-09-02T19:08:53-dbf442b/linux-amd64-longtest

I suspect this sudden influx is actually a new issue related to #54885, and that the ARM issue is not quite the same.