Clean, replace web3 to ethers in old JS file

[gfournieriExec]

No description provided.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.50%. Comparing base (46b53f5) to head (451e026).
Report is 6 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #182   +/-   ##
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  Coverage    84.50%   84.50%           
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  Files           35       35           
  Lines         1084     1084           
  Branches       221      221           
========================================
  Hits           916      916           
  Misses         168      168           

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[Le-Caignec]

I recommend upgrading to Ethers v6 before merging this.

[zguesmi]

@Le-Caignec
This PR brings some required cleaning to be able to migrate to newer version of HH and Ethers.
We agree, migrating to Ethers v6 is one of the next steps.

[james-toussaint]

Thank you!