Fix zk cache expiration check (apache#8458)

### Motivation
Currently, zk cache is refreshed every time because the units of comparison are different(ns and ms).
We should check the zk cache expiration time in the same unit.

(cherry picked from commit 37453b5)

pulsar-zookeeper-utils/src/main/java/org/apache/pulsar/zookeeper/ZooKeeperCache.java

@@ -400,7 +400,7 @@ private <T> void checkAndRefreshExpiredEntry(String path, final Deserializer<T>
         if (result != null && result.isDone()) {
             Pair<Entry<Object, Stat>, Long> entryPair = result.getNow(null);
             if (entryPair != null && entryPair.getRight() != null) {
-                if ((System.nanoTime() - entryPair.getRight()) > TimeUnit.SECONDS.toMillis(cacheExpirySeconds)) {
+                if ((System.nanoTime() - entryPair.getRight()) > TimeUnit.SECONDS.toNanos(cacheExpirySeconds)) {
                     this.zkSession.get().getData(path, this, (rc, path1, ctx, content, stat) -> {
                         if (rc != Code.OK.intValue()) {
                             log.warn("Failed to refresh zookeeper-cache for {} due to {}", path, rc);