fix multiple results returned by eth_estimateGas

[bylingo]

• Targeted PR against correct branch (see CONTRIBUTING.md)

• [ ] Linked to github-issue with discussion and accepted design OR link to spec that describes this work.

• [ ] Wrote tests

• [ ] Updated relevant documentation (docs/)

• [ ] Added a relevant changelog entry to the Unreleased section in CHANGELOG.md

• [ ] Reviewed Files changed in the github PR explorer

---

For Admin Use:

• Added appropriate labels to PR (ex. wip, ready-for-review, docs)
• Reviewers Assigned
• Squashed all commits, uses message "Merge PR #XYZ: [title]" (coding standards)

[codecov-commenter]

Codecov Report

Merging #3223 (b00e47b) into dev (39c86b1) will increase coverage by 0.09%. The diff coverage is 63.63%.

:exclamation: Current head b00e47b differs from pull request most recent head df26def. Consider uploading reports for the commit df26def to get more accurate results

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@@            Coverage Diff             @@
##              dev    #3223      +/-   ##
==========================================
+ Coverage   36.46%   36.55%   +0.09%     
==========================================
  Files         444      444              
  Lines       46606    46622      +16     
==========================================
+ Hits        16993    17041      +48     
+ Misses      28347    28320      -27     
+ Partials     1266     1261       -5     

Impacted Files	Coverage Δ
app/config/config.go	26.87% <30.00%> (+0.14%)	:arrow_up:
app/rpc/namespaces/eth/utils.go	32.00% <88.88%> (-7.72%)	:arrow_down:
app/test_helpers.go	92.15% <92.59%> (+0.49%)	:arrow_up:

... and 2 files with indirect coverage changes