add processing metric fun of name

[songxiaosheng]

What is the purpose of the change

add processing metric fun of name

change dubbo_provider_requests_processing to dubbo_provider_requests_processing_total

Brief changelog

Verifying this change

Checklist

• Make sure there is a GitHub_issue field for the change (usually before you start working on it). Trivial changes like typos do not require a GitHub issue. Your pull request should address just this issue, without pulling in other changes - one PR resolves one issue.
• Each commit in the pull request should have a meaningful subject line and body.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Check if is necessary to patch to Dubbo 3 if you are work on Dubbo 2.7
• Write necessary unit-test to verify your logic correction, more mock a little better when cross module dependency exist. If the new feature or significant change is committed, please remember to add sample in dubbo samples project.
• Add some description to dubbo-website project if you are requesting to add a feature.
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• If this contribution is large, please follow the Software Donation Guide.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

100.0% Coverage
0.0% Duplication

[codecov-commenter]

Codecov Report

Merging #12461 (700288a) into 3.2 (d6661cf) will decrease coverage by 0.23%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##                3.2   #12461      +/-   ##
============================================
- Coverage     69.60%   69.38%   -0.23%     
+ Complexity      340        2     -338     
============================================
  Files          3466     1622    -1844     
  Lines        163488    66849   -96639     
  Branches      27413     9798   -17615     
============================================
- Hits         113798    46380   -67418     
+ Misses        39731    15986   -23745     
+ Partials       9959     4483    -5476     

see 1863 files with indirect coverage changes

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