runtime: TestGoroutineLeakProfile failures under mayMoreStackPreempt

[mknyszek]

#!watchflakes
default <- pkg == "runtime:mayMoreStackPreempt" && test ~ `TestGoroutineLeakProfile`

Specifically, it seems that a bunch of leaks are no longer detected, but off-hand I can't tell why. I assume that maybe the check fires too early? Maybe goroutines don't get a chance to settle into their leaked state?

I'll send a change to skip the tests under mayMoreStackPreempt for now.

CC @VladSaiocUber

[mknyszek]

To reproduce: GOFLAGS=-gcflags=runtime=-d=maymorestack=runtime.mayMoreStackPreempt go test -run=TestGoroutineLeakProfile -v runtime

For context, this debug mode forces a scheduler preemption at every possible synchronous preemption point.

[gopherbot]

Change https://go.dev/cl/708715 mentions this issue: runtime: skip TestGoroutineLeakProfile under mayMoreStackPreempt