Configure for multi-tenant clusters (#18)

pass X-Scope-Orgid headers to make it work with multi-tenant tempo clusters.

without this change, it fails to push data to tempo clusters that have multitenancy_enabled: true need x-scope-orgid headers, and tempo clusters with multitenancy_enabled: false will ignore x-scope-orgid headers.

so set x-scope-orgid headers to make it work multitenancy_enabled: true clusters.

Author: electron0zero

examples/template/template.js

@@ -8,10 +8,14 @@ export const options = {
 };
 
 const endpoint = __ENV.ENDPOINT || "otel-collector:4317"
+const orgid = __ENV.TEMPO_X_SCOPE_ORGID || "k6-test"
 const client = new tracing.Client({
     endpoint,
     exporter: tracing.EXPORTER_OTLP,
     insecure: true,
+    headers: {
+        "X-Scope-Orgid": orgid
+    }
 });
 
 const traceDefaults = {