test: added test for TestMergeProcessFileCallBack different content case

[satyazzz123]

i) this test for source and destination files with different content on execution of MergeProcessFileCallBack funcion

fixes a part of #881

[github-actions]

Thanks for making a pull request! 😃
One of the maintainers will review and advise on the next steps.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 14.91%. Comparing base (e53812c) to head (5e6ba40).
Report is 1 commits behind head on main.

❗ Current head 5e6ba40 differs from pull request most recent head ba0231a. Consider uploading reports for the commit ba0231a to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1129      +/-   ##
==========================================
+ Coverage   14.89%   14.91%   +0.02%     
==========================================
  Files          90       90              
  Lines        8380     8380              
==========================================
+ Hits         1248     1250       +2     
+ Misses       6809     6805       -4     
- Partials      323      325       +2     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[satyazzz123]

@kmehant @seshapad @HarikrishnanBalagopal I have raised a PR. Please take a look . Thank you

[HarikrishnanBalagopal]

LGTM