Fixes JAVA-6094

Update attribute name for OpenTelemetry

Author: nhachicha

driver-core/src/main/com/mongodb/internal/observability/micrometer/MongodbObservation.java

@@ -76,7 +76,7 @@ public enum OperationLowCardinalityKeyNames implements KeyName {
         SYSTEM {
             @Override
             public String asString() {
-                return "db.system";
+                return "db.system.name";
             }
         },
         NAMESPACE {
@@ -113,7 +113,7 @@ public enum CommandLowCardinalityKeyNames implements KeyName {
         SYSTEM {
             @Override
             public String asString() {
-                return "db.system";
+                return "db.system.name";
             }
         },
         NAMESPACE {