[fix](jvm)fix jvm metrics memory leak.

[hubgeter]

What problem does this PR solve?

fix jvm metrics memory leak.

when you set enable_jvm_monitor=true in be.conf, you can find that be jvm memory is slowly growing.
By analyzing the hprof file, we can find that there are a large number of java.lang.management.ThreadInfo objects.
The specific cause of the memory leak is: jni does not manually delete the local reference after getting the object from the array, resulting in the object not being GC.

Issue Number: close #xxx

Related PR: #xxx

Problem Summary:

Release note

None

Check List (For Author)

• Test

  • Regression test
  • Unit Test
  • Manual test (add detailed scripts or steps below)
  • No need to test or manual test. Explain why:
    • This is a refactor/code format and no logic has been changed.
    • Previous test can cover this change.
    • No code files have been changed.
    • Other reason
      just fix memory leak no logic has been changed

• Behavior changed:

  • No.
  • Yes.

• Does this need documentation?

  • No.
  • Yes.

Check List (For Reviewer who merge this PR)

• Confirm the release note
• Confirm test cases
• Confirm document
• Add branch pick label

[doris-robot]

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1. What problem was fixed (it's best to include specific error reporting information). How it was fixed.
2. Which behaviors were modified. What was the previous behavior, what is it now, why was it modified, and what possible impacts might there be.
3. What features were added. Why was this function added?
4. Which code was refactored and why was this part of the code refactored?
5. Which functions were optimized and what is the difference before and after the optimization?

[hubgeter]

run buildall

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"