HDFS-17813. NameCache promote wrong name to cache map

[khazhen]

Description of PR

Refer to HDFS-17813.

The NameCache class is used to cache frequently used names in namenode, it promotes a name used more than useThreshold to the cache, the promote logic:

K put(final K name) {
  K internal = cache.get(name);
  if (internal != null) {
    lookups++;
    return internal;
  }

  // Track the usage count only during initialization
  if (!initialized) {
    UseCount useCount = transientMap.get(name);
    if (useCount != null) {
      useCount.increment();
      if (useCount.get() >= useThreshold) {
        promote(name); // name got promoted
      }
      return useCount.value;
    }
    useCount = new UseCount(name);
    transientMap.put(name, useCount);
  }
  return null;
} 

When promoting, the cache stores the name parameter from put() instead of the existing useCount.value. This causes the returned value to change after a name is promoted, resulting in memory duplication.

[hadoop-yetus]

💔 -1 overall

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			_ trunk Compile Tests _
+1 💚	mvninstall	25m 57s		trunk passed
+1 💚	compile	0m 48s		trunk passed with JDK Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04
+1 💚	compile	0m 42s		trunk passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
+1 💚	checkstyle	0m 38s		trunk passed
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+1 💚	javadoc	1m 9s		trunk passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
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			_ Patch Compile Tests _
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+1 💚	javac	0m 41s		the patch passed
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+1 💚	javadoc	0m 58s		the patch passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
+1 💚	spotbugs	1m 38s		the patch passed
+1 💚	shadedclient	21m 45s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
+1 💚	unit	90m 26s		hadoop-hdfs in the patch passed.
+1 💚	asflicense	0m 28s		The patch does not generate ASF License warnings.
		173m 5s

Subsystem	Report/Notes
Docker	ClientAPI=1.51 ServerAPI=1.51 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-7829/1/artifact/out/Dockerfile
GITHUB PR	#7829
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