[Metricbeat] Remove checking region/zone and service name from googlecloud

[kaiyan-sheng]

What does this PR do?

This PR is to remove validations for region/zone/service name in order for stackdriver metricset to work for wider services.

Why is it important?

service is only used to check when adding metadata and this is only available for compute metricset right now.

region/zone is not required for making ListTimeSeriesRequest API.

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. Enable googlecloud in Metricbeat
   ./metricbeat modules enable googlecloud

2. Modify modules.d/googlecloud.yml to use stackdriver metricset to collect logging metrics:

- module: googlecloud
  metricsets:
    - stackdriver
  project_id: elastic-observability
  credentials_file_path: "/Users/kaiyansheng/Downloads/elastic-observability-d17781618202.json"
  exclude_labels: false
  period: 1m
  stackdriver:
    service: billing
    metrics:
      - aligner: ALIGN_NONE
        metric_types:
          - "logging.googleapis.com/billing/bytes_ingested"
          - "logging.googleapis.com/byte_count"

3. Start metricbeat:

./metricbeat -e

4. You should see metrics in Kibana like:
   googlecloud.stackdriver.byte_count.value and googlecloud.stackdriver.billing.bytes_ingested.value

5. Change modules.d/googlecloud.yml to collect compute metrics and also should work:

- module: googlecloud
  metricsets:
    - stackdriver
  project_id: "your project id"
  credentials_file_path: "your JSON credentials file path"
  exclude_labels: false
  period: 1m
  period: 1m
  stackdriver:
    service: compute
    metrics:
      - aligner: ALIGN_NONE
        metric_types:
          - "compute.googleapis.com/instance/cpu/reserved_cores"
          - "compute.googleapis.com/instance/cpu/usage_time"
          - "compute.googleapis.com/instance/cpu/utilization"
          - "compute.googleapis.com/instance/uptime"

Related issues

• Closes [Metricbeat] Add stackdriver metricset for googlecloud module #16785

[elasticmachine]

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

[elasticmachine]

💚 Build Succeeded

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Build stats

• Build Cause: [Pull request [Metricbeat] Remove checking region/zone and service name from googlecloud #18398 updated]

• Start Time: 2020-05-11T21:15:51.157+0000

• Duration: 70 min 13 sec (4212600)

• Commit: 7064a16

Test stats 🧪

Test	Results
Failed	0
Passed	3022
Skipped	756
Total	3778

[blakerouse]

Looks good to me. Once comment about the nil check you added.