Update backend group name with a prefix

[salonichf5]

Proposed changes

Write a clear and concise description that helps reviewers understand the purpose and impact of your changes. Use the
following format:

Problem: User want to configure split client upstream in a namespace starting with a digit without running into any issues.

When a user was configuring split clients in a namespace starting with a digit, it led to proxy_pass variable being http://$9c_network__some_route_name_rule0$request_uri , which led to issues with nginx since variable names cannot start with a digit, leading to a 502 Bad Gateway error. The above problem existed for cases when a variable name is mentioned for using split weightage of upstreams.

Solution: Updated backend group name with a prefix "group_". Hence, we update split client variable names, distribution names and upstream names.

Testing: Testing with cafe and traffic splitting example.

Config with cafe example

location = /coffee {
       proxy_pass http://9test_coffee_80$request_uri;
    }
    location = /tea {
       proxy_pass http://9test_tea_80$request_uri;
    }


upstream 9test_coffee_80 {
    random two least_conn;
    zone 9test_coffee_80 512k;

    server 10.244.0.40:8080;
}

upstream 9test_tea_80 {
    random two least_conn;
    zone 9test_tea_80 512k;

    server 10.244.0.41:8080;
}

Config with trafic-splitting example

location /coffee/ {
        proxy_pass http://$group_9test__cafe_route_rule0$request_uri;
    }

location = /coffee {
       proxy_pass http://$group_9test__cafe_route_rule0$request_uri;
 }

upstream 9test_coffee-v1_80 {
    random two least_conn;
    zone 9test_coffee-v1_80 512k;

    server 10.244.0.38:8080;
}

upstream 9test_coffee-v2_80 {
    random two least_conn;
    zone 9test_coffee-v2_80 512k;

    server 10.244.0.39:8080;
}

split_clients $request_id $group_9test__cafe_route_rule0 {
    80.00% 9test_coffee-v1_80;
    20.00% 9test_coffee-v2_80;
}

Please focus on (optional): If you any specific areas where you would like reviewers to focus their attention or provide
specific feedback, add them here.

Closes #2606

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• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

Release notes

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please add a brief note that summarizes the change.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.40%. Comparing base (fed4239) to head (781816f).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2730      +/-   ##
==========================================
+ Coverage   89.38%   89.40%   +0.01%     
==========================================
  Files         110      110              
  Lines       10913    10913              
  Branches       50       50              
==========================================
+ Hits         9755     9757       +2     
+ Misses       1100     1098       -2     
  Partials       58       58              

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[sjberman]

Be sure to use your fork in the future, this doesn't need to be a branch on the main repo.

[salonichf5]

Be sure to use your fork in the future, this doesn't need to be a branch on the main repo.

Thank you for noticing that ! Need to fix my setup, probably messed it up !