[gcp] Remove emtpy values, names with only dots, and invalid client IPs.

[marc-gr]

What does this PR do?

Some gcp events contain keys that are formed only by dots, and also can contain invalid ip fields. This change cleans up both.

Checklist

• I have reviewed tips for building integrations and this pull request is aligned with them.
• I have verified that all data streams collect metrics or logs.
• I have added an entry to my package's changelog.yml file.
• I have verified that Kibana version constraints are current according to guidelines.

[elasticmachine]

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• Start Time: 2022-03-02T09:40:36.278+0000

• Duration: 27 min 30 sec

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Test	Results
Failed	0
Passed	28
Skipped	0
Total	28

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