feat: add request_ip as fallback for mixpanel group call

[Gauravudia]

What are the changes introduced in this PR?

• Added request_ip as a fallback IP for the Mixpanel group call. The priority order for mapping is context.ip followed by request_ip.
• This mapping is already supported in the identify call.
• RudderStack automatically collects user ip in request_ip . Ref:-https://www.rudderstack.com/docs/event-spec/standard-events/common-fields/#common-fields

What is the related Linear task?

Resolves INT-1978

Please explain the objectives of your changes below

Put down any required details on the broader aspect of your changes. If there are any dependent changes, mandatorily mention them here

Any changes to existing capabilities/behaviour, mention the reason & what are the changes ?

N/A

Any new dependencies introduced with this change?

N/A

Any new generic utility introduced or modified. Please explain the changes.

N/A

Any technical or performance related pointers to consider with the change?

N/A

@coderabbitai review

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Developer checklist

• My code follows the style guidelines of this project

• No breaking changes are being introduced.

• All related docs linked with the PR?

• All changes manually tested?

• Any documentation changes needed with this change?

• Is the PR limited to 10 file changes?

• Is the PR limited to one linear task?

• Are relevant unit and component test-cases added?

Reviewer checklist

• Is the type of change in the PR title appropriate as per the changes?

• Verified that there are no credentials or confidential data exposed with the changes.

[devops-github-rudderstack]

Test report for this run is available at: https://test-integrations-dev.s3.amazonaws.com/integrations-test-reports/rudder-transformer/3421/test-report.html

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.02%. Comparing base (cd0b81b) to head (e125ad2).
Report is 4 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3421      +/-   ##
===========================================
+ Coverage    88.01%   88.02%   +0.01%     
===========================================
  Files          569      570       +1     
  Lines        30634    30773     +139     
  Branches      7323     7351      +28     
===========================================
+ Hits         26961    27089     +128     
- Misses        3366     3377      +11     
  Partials       307      307              

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The base branch was changed.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
66.7% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud