[close #552] delete Netty Allocator on grafana (#553)

[ti-srebot]

cherry-pick #553 to release-3.1
You can switch your code base to this Pull Request by using git-extras:

# In client-java repo:
git pr https://github.com/tikv/client-java/pull/568

After apply modifications, you can push your change to this PR via:

git push [email protected]:ti-srebot/client-java.git pr/568:release-3.1-7278d5aa1d2a

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Signed-off-by: marsishandsome [email protected]

What problem does this PR solve?

Issue Number: close #552

Problem Description: Display problem with Netty Allocator on grafana

What is changed and how it works?

Delete Netty Allocator on grafana

[ti-srebot]

/run-all-tests

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (release-3.1@ea65650). Click here to learn what that means.
The diff coverage is n/a.

@@              Coverage Diff               @@
##             release-3.1     #568   +/-   ##
==============================================
  Coverage               ?   29.35%           
  Complexity             ?     1146           
==============================================
  Files                  ?      263           
  Lines                  ?    16567           
  Branches               ?     1896           
==============================================
  Hits                   ?     4863           
  Misses                 ?    11179           
  Partials               ?      525           

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