fix: auth0 error handling for missing userId

[Gauravudia]

What are the changes introduced in this PR?

• Removing this user_id required check for auth0 source.
• Auth0 source does not always sends user_id for each request. In case of failed logins with bad email addresses, user_id will be empty and there is no other relevant field that we could map with anonymousId
• Generate anonymousId for auth0 source.
• Refactor and use component testcases

What is the related Linear task?

Resolves INT-2065

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/3334/test-report.html

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.87%. Comparing base (129a0a1) to head (eb5d9e8).

Additional details and impacted files

@@                 Coverage Diff                 @@
##           hotfix/May.6th    #3334       +/-   ##
===================================================
+ Coverage                0   87.87%   +87.87%     
===================================================
  Files                   0      558      +558     
  Lines                   0    30063    +30063     
  Branches                0     7194     +7194     
===================================================
+ Hits                    0    26417    +26417     
- Misses                  0     3343     +3343     
- Partials                0      303      +303     

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
97.4% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud