Change at which level klog.Fatal is invoked

[soltysh]

What type of PR is this?
/kind bug
/kind cleanup
/kind regression
/sig cli
/priority important-longterm

What this PR does / why we need it:
With klog/v2 and specifically this PR: kubernetes/klog#79 we suddenly are logging excessive amount of data at level 2 already. Example is, when any command returns an error and it was invoked with -v=2 the error will be accompanied with full stack trace, example:

$ kubectl get --raw=/healthz -v=2
F0909 21:50:59.912233   48492 helpers.go:115] Unable to connect to the server: dial tcp: lookup api.localhost on 127.0.0.1:53: no such host
goroutine 1 [running]:
k8s.io/kubernetes/vendor/k8s.io/klog/v2.stacks(0xc00000e001, 0xc0006f8c00, 0xac, 0xfd)
	/workspace/k8s/src/k8s.io/kubernetes/_output/local/go/src/k8s.io/kubernetes/vendor/k8s.io/klog/v2/klog.go:996 +0xb8
k8s.io/kubernetes/vendor/k8s.io/klog/v2.(*loggingT).output(0x2f69600, 0xc000000003, 0x0, 0x0, 0xc00014a000, 0x2d42550, 0xa, 0x73, 0x40a200)
	/workspace/k8s/src/k8s.io/kubernetes/_output/local/go/src/k8s.io/kubernetes/vendor/k8s.io/klog/v2/klog.go:945 +0x19d
k8s.io/kubernetes/vendor/k8s.io/klog/v2.(*loggingT).printDepth(0x2f69600, 0x3, 0x0, 0x0, 0x2, 0xc000555ab0, 0x1, 0x1)
	/workspace/k8s/src/k8s.io/kubernetes/_output/local/go/src/k8s.io/kubernetes/vendor/k8s.io/klog/v2/klog.go:718 +0x15e
k8s.io/kubernetes/vendor/k8s.io/klog/v2.FatalDepth(...)
	/workspace/k8s/src/k8s.io/kubernetes/_output/local/go/src/k8s.io/kubernetes/vendor/k8s.io/klog/v2/klog.go:1442
k8s.io/kubernetes/vendor/k8s.io/kubectl/pkg/cmd/util.fatal(0xc00004c400, 0x7d, 0x1)
	/workspace/k8s/src/k8s.io/kubernetes/_output/local/go/src/k8s.io/kubernetes/vendor/k8s.io/kubectl/pkg/cmd/util/helpers.go:93 +0x1e8
k8s.io/kubernetes/vendor/k8s.io/kubectl/pkg/cmd/util.checkErr(0x1e50140, 0xc00097c1e0, 0x1c7ff98)
	/workspace/k8s/src/k8s.io/kubernetes/_output/local/go/src/k8s.io/kubernetes/vendor/k8s.io/kubectl/pkg/cmd/util/helpers.go:188 +0x958
k8s.io/kubernetes/vendor/k8s.io/kubectl/pkg/cmd/util.CheckErr(...)
	/workspace/k8s/src/k8s.io/kubernetes/_output/local/go/src/k8s.io/kubernetes/vendor/k8s.io/kubectl/pkg/cmd/util/helpers.go:115
k8s.io/kubernetes/vendor/k8s.io/kubectl/pkg/cmd/get.NewCmdGet.func1(0xc0002e7b80, 0xc0004737a0, 0x0, 0x2)
	/workspace/k8s/src/k8s.io/kubernetes/_output/local/go/src/k8s.io/kubernetes/vendor/k8s.io/kubectl/pkg/cmd/get/get.go:167 +0x151
k8s.io/kubernetes/vendor/github.com/spf13/cobra.(*Command).execute(0xc0002e7b80, 0xc000473760, 0x2, 0x2, 0xc0002e7b80, 0xc000473760)
	/workspace/k8s/src/k8s.io/kubernetes/_output/local/go/src/k8s.io/kubernetes/vendor/github.com/spf13/cobra/command.go:846 +0x29d
k8s.io/kubernetes/vendor/github.com/spf13/cobra.(*Command).ExecuteC(0xc0000ca840, 0xc00007e180, 0xc00003a080, 0x4)
	/workspace/k8s/src/k8s.io/kubernetes/_output/local/go/src/k8s.io/kubernetes/vendor/github.com/spf13/cobra/command.go:950 +0x349
k8s.io/kubernetes/vendor/github.com/spf13/cobra.(*Command).Execute(...)
	/workspace/k8s/src/k8s.io/kubernetes/_output/local/go/src/k8s.io/kubernetes/vendor/github.com/spf13/cobra/command.go:887
main.main()
	_output/local/go/src/k8s.io/kubernetes/cmd/kubectl/kubectl.go:49 +0x21d

goroutine 6 [chan receive]:
k8s.io/kubernetes/vendor/k8s.io/klog/v2.(*loggingT).flushDaemon(0x2f69600)
	/workspace/k8s/src/k8s.io/kubernetes/_output/local/go/src/k8s.io/kubernetes/vendor/k8s.io/klog/v2/klog.go:1131 +0x8b
created by k8s.io/kubernetes/vendor/k8s.io/klog/v2.init.0
	/workspace/k8s/src/k8s.io/kubernetes/_output/local/go/src/k8s.io/kubernetes/vendor/k8s.io/klog/v2/klog.go:416 +0xd6

goroutine 17 [select]:
k8s.io/kubernetes/vendor/k8s.io/apimachinery/pkg/util/wait.BackoffUntil(0x1c7fed0, 0x1e4e800, 0xc0005ee000, 0x1, 0xc000054120)
	/workspace/k8s/src/k8s.io/kubernetes/_output/local/go/src/k8s.io/kubernetes/vendor/k8s.io/apimachinery/pkg/util/wait/wait.go:167 +0x13f
k8s.io/kubernetes/vendor/k8s.io/apimachinery/pkg/util/wait.JitterUntil(0x1c7fed0, 0x12a05f200, 0x0, 0x1, 0xc000054120)
	/workspace/k8s/src/k8s.io/kubernetes/_output/local/go/src/k8s.io/kubernetes/vendor/k8s.io/apimachinery/pkg/util/wait/wait.go:133 +0x98
k8s.io/kubernetes/vendor/k8s.io/apimachinery/pkg/util/wait.Until(0x1c7fed0, 0x12a05f200, 0xc000054120)
	/workspace/k8s/src/k8s.io/kubernetes/_output/local/go/src/k8s.io/kubernetes/vendor/k8s.io/apimachinery/pkg/util/wait/wait.go:90 +0x4d
created by k8s.io/kubernetes/vendor/k8s.io/kubectl/pkg/util/logs.InitLogs
	/workspace/k8s/src/k8s.io/kubernetes/_output/local/go/src/k8s.io/kubernetes/vendor/k8s.io/kubectl/pkg/util/logs/logs.go:51 +0x96

This PR proposes to delay that stack to -v=4 since levels 1 and 2 are mostly used for information purposes and having this there seems an overkill. If you use kubectl prior to 1.19 those are not printed at all.

Special notes for your reviewer:
/assign @pwittrock @seans3

Does this PR introduce a user-facing change?:

Print go stack traces at -v=4 and not -v=2

[soltysh]

/hold
for longer exposure and agreement on the approach, we'll probably discuss this during next SIG-CLI which is in 2 weeks.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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[soltysh]

/hold cancel

[soltysh]

/retest

[soltysh]

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[soltysh]

/assign @sallyom

[sallyom]

/lgtm

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