Cherry-pick #26479 to 7.x: [metricbeat] Add state_job metricset

[ChrsMark]

Cherry-pick of PR #26479 to 7.x branch. Original message:

Add a Metricbeat metricset for Kubernetes Job resources.

What does this PR do?

Adds a state_job metricset to the Metricbeat Kubernetes module. Follows the established pattern of consuming Kube State Metrics output.

Why is it important?

Enables monitoring and alerting for Kubernetes Jobs.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

How to test this PR locally

1. Run unit tests

$ MODULE=kubernetes mage -v test

2. Deploy Metricbeat and enable this metricset. Verify that metrics about Jobs are being collected as expected along with k8s metadata.

[elasticmachine]

Pinging @elastic/integrations (Team:Integrations)

[elasticmachine]

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• Build Cause: ChrsMark commented: /test

• Start Time: 2021-07-02T07:47:24.207+0000

• Duration: 106 min 12 sec

• Commit: ddc6c5f

Test stats 🧪

Test	Results
Failed	0
Passed	31577
Skipped	3946
Total	35523

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Test stats 🧪

Test	Results
Failed	0
Passed	31577
Skipped	3946
Total	35523

[ChrsMark]

/test