GCP metrics: Missing ECS labels when using exclude_labels: true

[gpop63]

The GCP metrics metricset's exclude_labels: true option causes an issue in the groupTimeSeries function. The default metadata collector is created as a value, preventing the function from initializing metadataService with the correct time series data. This results in missing important labels like cloud.instance.id in the events. To fix this, metadataService should be initially set to nil, allowing initialization based on the time series parameter.

var metadataService gcp.MetadataService

[botelastic]

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