Adjust host fields in Metricbeat to use ECS 1.9.0 field names

[kaiyan-sheng]

What does this PR do?

With additional host fields get into ECS 1.9.0, we need to adjust the fields we added into Metricbeat to adopt the ECS field names.

• system module
• aws module
• azure module
• gcp module

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.

[elasticmachine]

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Build stats

• Build Cause: Pull request #24312 updated

• Start Time: 2021-04-27T19:29:34.729+0000

• Duration: 168 min 40 sec

• Commit: 271b96b

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Failed	0
Passed	46637
Skipped	5129
Total	51766

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Test	Results
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Passed	46637
Skipped	5129
Total	51766

[kaiyan-sheng]

/test

[elasticmachine]

Pinging @elastic/integrations (Team:Integrations)

[narph]

@kaiyan-sheng , have you checked if these changes affected any of the dashboards? I have a feeling we are using some of the fields in the visualizations?

[sayden]

All good! But I haven't checked the dashboards though

[kaiyan-sheng]

Thanks @sayden @narph ! These fields are brand new actually, we added them when we started the inventory schema work. So they are not used in any dashboards or visualizations yet. They will be adopted in kibana metrics UI soon and that's why I want to get this in soon so the UI doesn't have to make the naming change again.