fix: evm signer tests were failing intermittently in CI

[kevinssgh]

Description

Changed test eth signer type to support more transaction types.

Closes: #1887

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Include instructions and any relevant details so others can reproduce.

• Tested CCTX in localnet
• Go unit tests
• Go integration tests
• Tested via GitHub Actions

Checklist:

• I have added unit tests that prove my fix feature works

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 52.12%. Comparing base (8146f92) to head (4563ace).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #1944   +/-   ##
========================================
  Coverage    52.12%   52.12%           
========================================
  Files          235      235           
  Lines        13347    13347           
========================================
  Hits          6957     6957           
  Misses        5953     5953           
  Partials       437      437           

Files	Coverage Δ
zetaclient/evm/evm_signer.go	48.44% <100.00%> (ø)