[VER] Patch verification integration code

[ramtinms]

This PR :

• patches the test logic to create fixtures for integration tests
• fixes the issue in the chunk verifier on what tx index to use for system chunk transaction

[codecov-commenter]

Codecov Report

Merging #952 (b728759) into master (98dc4aa) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #952   +/-   ##
=======================================
  Coverage   54.92%   54.92%           
=======================================
  Files         277      277           
  Lines       18342    18342           
=======================================
  Hits        10075    10075           
  Misses       6903     6903           
  Partials     1364     1364           

Flag	Coverage Δ
unittests	54.92% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
engine/execution/convert.go	88.88% <100.00%> (ø)
module/chunks/chunkVerifier.go	64.76% <100.00%> (ø)

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