client/pkg/testutil: add shouldSkip func for interestingGoroutines

[callthingsoff]

interestingGoroutines uses so many strings.Contains checks to determine
whether to continue, I think it can be avoided.

This patch introduces shouldSkip func to do the checks in a loop
to make the logic clearer.

Please read https://github.com/etcd-io/etcd/blob/main/CONTRIBUTING.md#contribution-flow.

[k8s-ci-robot]

Hi @callthingsoff. Thanks for your PR.

I'm waiting for a etcd-io member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[jmhbnz]

/ok-to-test

[ahrtr]

Suggested change:

func interestingGoroutines() (gs []string) {
	buf := make([]byte, 2<<20)
	buf = buf[:runtime.Stack(buf, true)]
	for _, g := range strings.Split(string(buf), "\n\n") {
		sl := strings.SplitN(g, "\n", 2)
		if len(sl) != 2 {
			continue
		}
		stack := strings.TrimSpace(sl[1])
		if stack == "" {
			continue
		}
		
		shouldSkip := func() bool {
			var uninterestingMsgs = [...]string{
				"sync.(*WaitGroup).Done",
				"os.(*file).close",
				"os.(*Process).Release",
				"created by os/signal.init",
				"runtime/panic.go",
				"created by testing.RunTests",
				"created by testing.runTests",
				"created by testing.(*T).Run",
				"testing.Main(",
				"runtime.goexit",
				"go.etcd.io/etcd/client/pkg/v3/testutil.interestingGoroutines",
				"go.etcd.io/etcd/client/pkg/v3/logutil.(*MergeLogger).outputLoop",
				"github.com/golang/glog.(*loggingT).flushDaemon",
				"created by runtime.gc",
				"created by text/template/parse.lex",
				"runtime.MHeap_Scavenger",
				"rcrypto/internal/boring.(*PublicKeyRSA).finalize",
				"net.(*netFD).Close(",
				"testing.(*T).Run",
			}
			for _, msg := range uninterestingMsgs {
				if strings.Contains(stack, msg) {
					return true
				}
			}
			return false
		}()

		if shouldSkip {
			continue
		}

		gs = append(gs, stack)
	}
	sort.Strings(gs)
	return gs
}

[jmhbnz]

LGTM