OLS-2604 add google vertex provider

[raptorsun]

Description

This PR adds Google Vertex AI as a provider.
It has 2 types google_vertex and google_vertex_anthropic, for generic model and Claude models respectively.
This only works in combination of the service PR openshift/lightspeed-service#2877

I typical config for google vertex provider can be:

apiVersion: ols.openshift.io/v1alpha1
kind: OLSConfig
metadata:
  name: cluster
spec:
  llm:
    providers:
      - type: google_vertex
        googleVertexConfig:
          projectID: project-220c95dd-dc02-4f3f-a9a
          location: us-east5
        credentialsSecretRef:
          name: google-vertex-secret
        credentialKey: apitoken
        models:
          - name: gemini-2.5-flash
        name: google_vertex
        url: "https://us-east5-aiplatform.googleapis.com"

  ols:
    introspectionEnabled: false
    byokRAGOnly: false
    defaultModel: gemini-2.5-flash
    defaultProvider: google_vertex
    logLevel: INFO

Type of change

• Refactor
• New feature
• Bug fix
• CVE fix
• Optimization
• Documentation Update
• Configuration Update
• Bump-up dependent library

Related Tickets & Documents

• Related Issue # https://redhat.atlassian.net/browse/OLS-2588
• Closes # OLS-2604

Checklist before requesting a review

• I have performed a self-review of my code.
• PR has passed all pre-merge test jobs.
• If it is a core feature, I have added thorough tests.

Testing

• Please provide detailed steps to perform tests related to this code change.
• How were the fix/results from this change verified? Please provide relevant screenshots or results.

[raptorsun]

/test bundle-e2e-4-21

[blublinsky]

This seems wrong. Vertex does not have to be first. Should be

or i, provider := range cr.Spec.LLMConfig.Providers {
if provider.Type == utils.GoogleVertexType || provider.Type == utils.GoogleVertexAnthropicType {
volumeName := fmt.Sprintf("google-vertex-credential-%d", i)
*volumes = append(*volumes, corev1.Volume{
Name: volumeName,
VolumeSource: corev1.VolumeSource{
Secret: &corev1.SecretVolumeSource{
SecretName: provider.CredentialsSecretRef.Name,
DefaultMode: volumeDefaultMode,
},
},
})
// ... corresponding mount
}
}

[blublinsky]

This test does not check not 1st vertex provider

[raptorsun]

Hello @blublinsky , I updated the code for better managing the vertex providers for llama stack backend.
There is a limitation that when using a credential file, we have to choose one file for the backend authentication using the env var GOOGLE_APPLICATION_CREDENTIALS. elsewise we should use the simple api token that lives very shortly obtained by oauth.
Maybe we can submit a issue for llama stack and we use one of the credential files of vertex provider for the llama stack backend. when llama stack support credential file parameter for vertex ai provider, we can update our operator code accordingly.

[blublinsky]

/lgtm
/approve

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

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[raptorsun]

/test bundle-e2e-4-21

[openshift-ci]

@raptorsun: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/bundle-e2e-4-21	25241be	link	unknown	/test bundle-e2e-4-21

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[openshift-merge-bot]

/retest-required

Remaining retests: 0 against base HEAD 861f8e6 and 2 for PR HEAD 25241be in total

[raptorsun]

/retest-required