Move errors and warnings to output to stderr

[tstromberg]

Fixes issue where we inadvertently pollute JSON output with "slow docker" warning: #7381

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: tstromberg

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[tstromberg]

/ok-to-test

[minikube-pr-bot]

Error: running mkcmp: exit status 1

[codecov-io]

Codecov Report

Merging #7382 into master will increase coverage by 0.00%.
The diff coverage is 4.34%.

@@           Coverage Diff           @@
##           master    #7382   +/-   ##
=======================================
  Coverage   37.18%   37.19%           
=======================================
  Files         145      145           
  Lines        8836     8850   +14     
=======================================
+ Hits         3286     3292    +6     
- Misses       5154     5161    +7     
- Partials      396      397    +1     

Impacted Files	Coverage Δ
cmd/minikube/cmd/config/profile.go	0.00% <0.00%> (ø)
cmd/minikube/cmd/config/profile_list.go	3.79% <0.00%> (ø)
cmd/minikube/cmd/delete.go	25.10% <0.00%> (ø)
cmd/minikube/cmd/logs.go	18.51% <0.00%> (ø)
cmd/minikube/cmd/mount.go	8.84% <0.00%> (ø)
cmd/minikube/cmd/node_add.go	25.00% <0.00%> (ø)
cmd/minikube/cmd/service.go	10.44% <0.00%> (ø)
cmd/minikube/cmd/start.go	34.34% <0.00%> (-0.27%)	⬇️
cmd/minikube/cmd/stop.go	0.00% <0.00%> (ø)
pkg/minikube/logs/logs.go	2.35% <0.00%> (ø)
... and 6 more

[minikube-pr-bot]

All Times Minikube (PR 7382): [ 62.940264 62.596238 64.452249]
All Times minikube: [ 66.631944 61.423714 62.523258]

Average minikube: 63.526305
Average Minikube (PR 7382): 63.329584

Averages Time Per Log

+----------------------+-----------+--------------------+
|         LOG          | MINIKUBE  | MINIKUBE (PR 7382) |
+----------------------+-----------+--------------------+
| minikube v           |  0.212487 |           0.214855 |
| Creating kvm2        | 40.225555 |          40.537585 |
| Preparing Kubernetes | 20.923259 |          20.802426 |
| Pulling images       |           |                    |
| Launching Kubernetes |           |                    |
| Waiting for cluster  |           |                    |
+----------------------+-----------+--------------------+

[minikube-pr-bot]

All Times minikube: [ 65.015572 63.226705 65.156055]
All Times Minikube (PR 7382): [ 67.311615 63.416269 63.117197]

Average minikube: 64.466111
Average Minikube (PR 7382): 64.615027

Averages Time Per Log

+----------------------+-----------+--------------------+
|         LOG          | MINIKUBE  | MINIKUBE (PR 7382) |
+----------------------+-----------+--------------------+
| minikube v           |  0.207278 |           0.208909 |
| Creating kvm2        | 41.368903 |          40.594703 |
| Preparing Kubernetes | 21.348727 |          22.358814 |
| Pulling images       |           |                    |
| Launching Kubernetes |           |                    |
| Waiting for cluster  |           |                    |
+----------------------+-----------+--------------------+

[medyagh]

following failures for for docker driver need confirmation PR reply that is not related to this PR.

• TestStartStop/group/old-docker - 550.49s
• TestStartStop/group/newest-cni - 111.26s
• TestStartStop/group/containerd - 191.43s
• TestStartStop/group/crio - 734.25s
• TestStartStop/group/embed-certs - 157.68s

[tstromberg]

Errors appear unrelated.