fix(google-cloud-spanner): Add credential check for built-in metrics enabling (#13038)

Author: zdu-strong

java-spanner/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerOptions.java

@@ -2729,7 +2729,7 @@ public void enablegRPCMetrics(
     // records each instrument once per GrpcOpenTelemetry instance, so wiring two instances onto one
     // channel does not double-count attempt/operation metrics (verified by
     // GrpcMetricsDualWireTest).
-    if (isEnableBuiltInMetrics()) {
+    if (isEnableBuiltInMetrics() && !usesNoCredentials()) {
       this.builtInMetricsProvider.enableGrpcMetrics(
           channelProviderBuilder,
           this.getProjectId(),