Perform SHA-256 Hash for Certificate Signature Validation

[hisanhunais]

Purpose

The PR [1] changed the default certificate hashing algorithm to SHA-256. This PR incorporates that change in to integration tests by performing SHA-256 hashing for certificate signature validation.

This should be merged after merging [1]

[1] wso2/carbon-apimgt#12365

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 20.52%. Comparing base (06a3b3e) to head (c38f92d).
Report is 359 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #13455      +/-   ##
============================================
+ Coverage     14.50%   20.52%   +6.01%     
- Complexity      748     1039     +291     
============================================
  Files           254      254              
  Lines         11489    11495       +6     
  Branches       1200     1200              
============================================
+ Hits           1667     2359     +692     
+ Misses         9804     9116     -688     
- Partials         18       20       +2     

Flag	Coverage Δ
integration_tests	20.52% <ø> (+6.01%)	⬆️

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[hisanhunais]

The default certificate hashing algorithm was kept as SHA-1 with [1] by reverting the change made to keep the default hashing algorithm as SHA-256. So, this change is not needed. Hence, closing the PR.

[1] wso2/carbon-apimgt#12387