fix: align empty account result for old blocks as ethereum (backport: #1484)

[mmsqe]

for more evmos#1484

Description

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For contributor use:

• 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.
• Code follows the module structure standards.
• Wrote unit and integration tests
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer

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For admin use:

• Added appropriate labels to PR (ex. WIP, R4R, docs, etc)
• Reviewers assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[codecov]

Codecov Report

Merging #221 (e706062) into release/v0.20.x-cronos (44a41ad) will decrease coverage by 0.04%.
The diff coverage is 0.00%.

@@                    Coverage Diff                     @@
##           release/v0.20.x-cronos     #221      +/-   ##
==========================================================
- Coverage                   57.35%   57.31%   -0.04%     
==========================================================
  Files                         108      108              
  Lines                       10090    10096       +6     
==========================================================
  Hits                         5787     5787              
- Misses                       4057     4063       +6     
  Partials                      246      246              

Impacted Files	Coverage Δ
rpc/backend/utils.go	8.67% <0.00%> (-0.32%)	⬇️