Remove fallback mechanism for the signed cookies from super tenant

[sadilchamishka]

Purpose

$subject

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 39.34%. Comparing base (cb7e045) to head (283a8dc).
Report is 10 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##             master     #199   +/-   ##
=========================================
  Coverage     39.34%   39.34%           
  Complexity      405      405           
=========================================
  Files           111      111           
  Lines          3604     3604           
  Branches        410      410           
=========================================
  Hits           1418     1418           
  Misses         2030     2030           
  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/12249672959

[jenkins-is-staging]

PR builder completed
Link: https://github.com/wso2/product-is/actions/runs/12249672959
Status: success

[jenkins-is-staging]

Approving the pull request based on the successful pr build https://github.com/wso2/product-is/actions/runs/12249672959

[indeewari]

• Create context specific tenanted keystore for seperate purposes like cookie creation wso2/product-is#21985