[GCP VertexAI] Remove zone filter and fix regions

[muthu-mps]

This PR removes the zone filter and fixes the regions filter default value.

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.
• I have verified that any added dashboard complies with Kibana's Dashboard good practices

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[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 961ca4974bfab8c6fb57d837f66d5f560bfcae8f

cc @muthu-mps

[elastic-sonarqube]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube

[ishleenk17]

Looks good!

[elastic-vault-github-plugin-prod]

Package gcp_vertexai - 0.3.1 containing this change is available at https://epr.elastic.co/package/gcp_vertexai/0.3.1/

[shmsr]

@muthu-mps But why did we remove the zone filter?

[muthu-mps]

@muthu-mps But why did we remove the zone filter?

The zone filter was removed to make it similar to what we have in other cloud providers and the zone comes under the region where we decide to keep only region filter.

cc: @ishleenk17

[shmsr]

Oh ok

[ishleenk17]

Moreso, we are now using regions (array) for taking the region as input from user.
Having a singular zone and multiple regions doesn't make sense together.

We can have region and zone together as input configs but not regions and zone.