Cherry-pick #22246 to 7.x: [Metricbeat] Rename googlecloud module to gcp module in Metricbeat

[kaiyan-sheng]

Cherry-pick of PR #22246 to 7.x branch. Original message:

What does this PR do?

This PR is to rename googlecloud module in Metricbeat to gcp module. Since this module is still in beta, I'm making this a breaking change to rename the 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.

How to test this PR locally

Test compute metricset by enabling gcp module first with ./metricbeat modules enable gcp and then edit modules.d/gcp.yml with:

- module: gcp
  metricsets:
    - compute
  region: "us-"
  project_id: "elastic-observability"
  credentials_file_path: "/Users/kaiyansheng/Desktop/elastic-observability-5537b831234a.json"
  exclude_labels: false
  period: 1m

Related issues

• Relates Fix inconsistency of GCP Filebeat/Metricbeat names #19467

[elasticmachine]

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

[botelastic]

This pull request doesn't have a Team:<team> label.

[elasticmachine]

💚 Build Succeeded

the below badges are clickable and redirect to their specific view in the CI or DOCS

Expand to view the summary

Build stats

• Build Cause: [Pull request #22405 updated]

• Start Time: 2020-11-03T21:43:51.009+0000

• Duration: 77 min 43 sec

Test stats 🧪

Test	Results
Failed	0
Passed	2757
Skipped	614
Total	3371

[elasticmachine]

💚 Flaky test report

Tests succeeded.

Expand to view the summary

Test stats 🧪

Test	Results
Failed	0
Passed	2757
Skipped	614
Total	3371