Don't recalculate which server was deletion ignored from in onAbsent,…

… instead use locally available value.

xds/src/main/java/io/grpc/xds/client/XdsClientImpl.java

@@ -919,7 +919,7 @@ void onAbsent(@Nullable ProcessingTracker processingTracker) {
         if (!resourceDeletionIgnored) {
           logger.log(XdsLogLevel.FORCE_WARNING,
               "xds server {0}: ignoring deletion for resource type {1} name {2}}",
-              getTarget(), type, resource);
+              activeCpc.getServerInfo().target(), type, resource);
           resourceDeletionIgnored = true;
         }
         return;