AMBARI-26596: Fixing fd leak during kerberizing

[HalimKim]

What changes were proposed in this pull request?

Using try-with-resources instead of just try in AbstractKerberosDescriptorFactory.java and AmbariMetaInfo.java

AbstractKerberosDescriptorFactory.java:

-      try {
-        return new Gson().fromJson(new FileReader(file),
+      try (FileReader reader = new FileReader(file)) {
+        return new Gson().fromJson(reader,
             new TypeToken<Map<String, Object>>() {
             }.getType());

AmbariMetaInfo.java:

-      try {
-        map = gson.fromJson(new FileReader(svc.getMetricsFile()), type);
+      try (FileReader reader = new FileReader(svc.getMetricsFile())) {
+        map = gson.fromJson(reader, type);

How was this patch tested?

manual tests done
I've built ambari-server jar file and updated my original ambari-server jar.
With the change, I've tried kerberizing test in my cluster.

[himanshumaurya09876]

Thanks for catching this and updating the FileReader usage to try-with-resources. It’s a clean improvement that helps prevent resource leaks and makes the code more robust. Appreciate the thoughtful fix.
Can you please check and fix at other places as well like Runner.java, ThemeModule.java etc.