chore(tools/bigquery&looker-conversational-analytics): add X-Goog-API-Client header (#2462)

## Description

Add X-Goog-API-Client header.

Change entry point to v1beta.

## PR Checklist

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[CONTRIBUTING.md](https://github.com/googleapis/genai-toolbox/blob/main/CONTRIBUTING.md)
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[bug/issue](https://github.com/googleapis/genai-toolbox/issues/new/choose)
  before writing your code! That way we can discuss the change, evaluate
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- [ ] Code coverage does not decrease (if any source code was changed)
- [ ] Appropriate docs were updated (if necessary)
- [ ] Make sure to add `!` if this involve a breaking change

🛠️ Fixes #<issue_number_goes_here>

internal/tools/bigquery/bigqueryconversationalanalytics/bigqueryconversationalanalytics.go

@@ -35,6 +35,8 @@ import (
 
 const resourceType string = "bigquery-conversational-analytics"
 
+const gdaURLFormat = "https://geminidataanalytics.googleapis.com/v1beta/projects/%s/locations/%s:chat"
+
 const instructions = `**INSTRUCTIONS - FOLLOW THESE RULES:**
 1. **CONTENT:** Your answer should present the supporting data and then provide a conclusion based on that data.
 2. **OUTPUT FORMAT:** Your entire response MUST be in plain text format ONLY.
@@ -236,11 +238,12 @@ func (t Tool) Invoke(ctx context.Context, resourceMgr tools.SourceProvider, para
 	if location == "" {
 		location = "us"
 	}
-	caURL := fmt.Sprintf("https://geminidataanalytics.googleapis.com/v1alpha/projects/%s/locations/%s:chat", projectID, location)
+	caURL := fmt.Sprintf(gdaURLFormat, projectID, location)
 
 	headers := map[string]string{
-		"Authorization": fmt.Sprintf("Bearer %s", tokenStr),
-		"Content-Type":  "application/json",
+		"Authorization":     fmt.Sprintf("Bearer %s", tokenStr),
+		"Content-Type":      "application/json",
+		"X-Goog-API-Client": util.GDAClientID,
 	}
 
 	payload := CAPayload{
@@ -252,7 +255,7 @@ func (t Tool) Invoke(ctx context.Context, resourceMgr tools.SourceProvider, para
 			},
 			Options: Options{Chart: ChartOptions{Image: ImageOptions{NoImage: map[string]any{}}}},
 		},
-		ClientIdEnum: "GENAI_TOOLBOX",
+		ClientIdEnum: util.GDAClientID,
 	}
 
 	// Call the streaming API

internal/tools/looker/lookerconversationalanalytics/lookerconversationalanalytics.go

@@ -267,8 +267,9 @@ func (t Tool) Invoke(ctx context.Context, resourceMgr tools.SourceProvider, para
 	caURL := fmt.Sprintf("https://geminidataanalytics.googleapis.com/v1beta/projects/%s/locations/%s:chat", url.PathEscape(projectID), url.PathEscape(location))
 
 	headers := map[string]string{
-		"Authorization": fmt.Sprintf("Bearer %s", tokenStr),
-		"Content-Type":  "application/json",
+		"Authorization":     fmt.Sprintf("Bearer %s", tokenStr),
+		"Content-Type":      "application/json",
+		"X-Goog-API-Client": util.GDAClientID,
 	}
 
 	payload := CAPayload{
@@ -280,7 +281,7 @@ func (t Tool) Invoke(ctx context.Context, resourceMgr tools.SourceProvider, para
 			},
 			Options: ConversationOptions{Chart: ChartOptions{Image: ImageOptions{NoImage: map[string]any{}}}},
 		},
-		ClientIdEnum: "GENAI_TOOLBOX",
+		ClientIdEnum: util.GDAClientID,
 	}
 
 	// Call the streaming API

internal/util/util.go

@@ -28,6 +28,9 @@ import (
 	"github.com/googleapis/genai-toolbox/internal/telemetry"
 )
 
+// GDAClientID is the client ID for Gemini Data Analytics
+const GDAClientID = "GENAI_TOOLBOX"
+
 // DecodeJSON decodes a given reader into an interface using the json decoder.
 func DecodeJSON(r io.Reader, v interface{}) error {
 	defer io.Copy(io.Discard, r) //nolint:errcheck