get greatest instead of just latest Kubernetes version

[prezha]

fixes #4392 (iteration 1 & 2)

fixing two mistakes i've previously made:

1. returning latest, but not necessarily also the greatest version (eg, Kubernetes released v1.18.10 after v1.19.3 but we need the latter)
2. comparing versions as strings, now using semver to check version validity, check if it's prerelease, and compare versions

and also fixed klog no such flag -logtostderr error

[k8s-ci-robot]

Hi @prezha. Thanks for your PR.

I'm waiting for a kubernetes 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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[codecov-io]

Codecov Report

Merging #9480 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #9480   +/-   ##
=======================================
  Coverage   29.05%   29.05%           
=======================================
  Files         171      171           
  Lines       10443    10443           
=======================================
  Hits         3034     3034           
  Misses       6987     6987           
  Partials      422      422           

[minikube-bot]

Can one of the admins verify this patch?

[sharifelgamal]

Thanks for fixing this!

/ok-to-test

[minikube-pr-bot]

kvm2 Driver
error collecting results for kvm2 driver: timing run 0 with Minikube (PR 9480): timing cmd: [/home/performance-monitor/.minikube/minikube-binaries/9480/minikube start --driver=kvm2]: starting cmd: fork/exec /home/performance-monitor/.minikube/minikube-binaries/9480/minikube: exec format error
docker Driver
error collecting results for docker driver: timing run 0 with Minikube (PR 9480): timing cmd: [/home/performance-monitor/.minikube/minikube-binaries/9480/minikube start --driver=docker]: starting cmd: fork/exec /home/performance-monitor/.minikube/minikube-binaries/9480/minikube: exec format error

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: medyagh, prezha

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