Fix accidental removal of a line

tracing/providers/opentelemetry/src/main/java/io/helidon/tracing/providers/opentelemetry/OpenTelemetryTracerProvider.java

@@ -169,6 +169,7 @@ public Tracer global() {
     public void global(Tracer tracer) {
         if (tracer instanceof OpenTelemetryTracer ott) {
             globalTracer(ott);
+            return;
         }
         throw new IllegalArgumentException("Tracer must be an instance of Helidon OpenTelemetry tracer. "
                                                    + "Please use HelidonOpenTelemetry to create such instance");