fix: disable afe_connectivity_error_count metric

Author: surbhigarg92

google-cloud-spanner/src/main/java/com/google/cloud/spanner/spi/v1/HeaderInterceptor.java

@@ -189,7 +189,9 @@ private void processHeader(
           float afeLatency = serverTimingMetrics.get(AFE_TIMING_HEADER);
           compositeTracer.recordAFELatency(afeLatency);
         } else {
-          compositeTracer.recordAfeHeaderMissingCount(1L);
+          // Disable afe_connectivity_error_count metric as AFE header is disabled in backend
+          // currently.
+          // compositeTracer.recordAfeHeaderMissingCount(1L);
         }
       }
     } catch (NumberFormatException e) {

google-cloud-spanner/src/test/java/com/google/cloud/spanner/OpenTelemetryBuiltInMetricsTracerTest.java

@@ -390,9 +390,9 @@ public void testNoServerTimingHeader() throws IOException, InterruptedException
 
     assertFalse(checkIfMetricExists(metricReader, BuiltInMetricsConstant.AFE_LATENCIES_NAME));
     assertFalse(checkIfMetricExists(metricReader, BuiltInMetricsConstant.GFE_LATENCIES_NAME));
-    MetricData afeConnectivityMetricData =
-        getMetricData(metricReader, BuiltInMetricsConstant.AFE_CONNECTIVITY_ERROR_NAME);
-    assertThat(getAggregatedValue(afeConnectivityMetricData, expectedAttributes)).isEqualTo(1);
+    // Metric is disabled currently
+    assertFalse(
+        checkIfMetricExists(metricReader, BuiltInMetricsConstant.AFE_CONNECTIVITY_ERROR_NAME));
 
     spannerNoHeader.close();
     serverNoHeader.shutdown();