Flatten BuildConfigFromFlags to avoid warning logs on k8s client creation

[ChrsMark]

What does this PR do?

This PR fixes #18961, by implementing client configuration creation on Beats side in order to avoid the annoying warning logs of client-go.

This happens by replacing

beats/libbeat/common/kubernetes/util.go

Line 52 in 0ef20cc

cfg, err := clientcmd.BuildConfigFromFlags("", kubeconfig)

call with a call to a method of ours which implements the same logic without the logging.

Why is it important?

In order to avoid the annoying warning logs of client-go.

Closes #18961

[elasticmachine]

Pinging @elastic/integrations-platforms (Team:Platforms)

[elasticmachine]

💚 Build Succeeded

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Build stats

• Build Cause: [Pull request #18964 updated, Started by user Chris Mark, Rebuilds build #2]

• Start Time: 2020-06-04T09:19:16.370+0000

• Duration: 80 min 56 sec

Test stats 🧪

Test	Results
Failed	0
Passed	9317
Skipped	1574
Total	10891

Steps errors

Expand to view the steps failures

• Name: Report to Codecov

  • Description: curl -sSLo codecov https://codecov.io/bash for i in auditbeat filebeat heartbeat libbeat metricbeat packetbeat winlogbeat journalbeat do FILE="${i}/build/coverage/full.cov" if [ -f "${FILE}" ]; then bash codecov -f "${FILE}" fi done

  • Duration: 1 min 27 sec

  • Start Time: 2020-06-04T10:22:50.801+0000

  • log

• Name: Report to Codecov

  • Description: curl -sSLo codecov https://codecov.io/bash for i in auditbeat filebeat heartbeat libbeat metricbeat packetbeat winlogbeat journalbeat do FILE="${i}/build/coverage/full.cov" if [ -f "${FILE}" ]; then bash codecov -f "${FILE}" fi done

  • Duration: 2 min 22 sec

  • Start Time: 2020-06-04T09:45:23.667+0000

  • log

• Name: Report to Codecov

  • Description: curl -sSLo codecov https://codecov.io/bash for i in auditbeat filebeat heartbeat libbeat metricbeat packetbeat winlogbeat journalbeat do FILE="${i}/build/coverage/full.cov" if [ -f "${FILE}" ]; then bash codecov -f "${FILE}" fi done

  • Duration: 2 min 22 sec

  • Start Time: 2020-06-04T10:08:21.415+0000

  • log

[exekias]

Great fix! I guess this doesn't require a changelog as the the client-go update was not released

[ChrsMark]

Great fix! I guess this doesn't require a changelog as the the client-go update was not released

Yeap, all this stuff targets 7.9.