Restrict cross-tenant Multi Attribute Login Identifier lookups

[HasiniSama]

Purpose

Restrict cross-tenant Multi-Attribute Login Identifier lookups to prevent unauthorized cross-tenant resolutions.

Goals

• Ensure login identifier resolution occurs only within the current tenant's context.
• Provide clearer debug messages for easier issue identification.

Approach

• Enforced tenant domain validation in the resolveMultiAttributeLoginIdentifier method.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 39.75%. Comparing base (17b92fc) to head (6de9beb).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##             master     #201   +/-   ##
=========================================
  Coverage     39.75%   39.75%           
  Complexity      408      408           
=========================================
  Files           111      111           
  Lines          3675     3675           
  Branches        416      416           
=========================================
  Hits           1461     1461           
  Misses         2058     2058           
  Partials        156      156           

Flag	Coverage Δ
unit	43.09% <ø> (ø)

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[jenkins-is-staging]

PR builder started
Link: https://github.com/wso2/product-is/actions/runs/12710126896

[jenkins-is-staging]

PR builder completed
Link: https://github.com/wso2/product-is/actions/runs/12710126896
Status: success

[jenkins-is-staging]

Approving the pull request based on the successful pr build https://github.com/wso2/product-is/actions/runs/12710126896