refactor: clean TestRejectedProposalDeposits

[facundomedica]

Description

This PR attempts to fix a flaky test. I did some cleanup of the function and so far I didn't encounter the issue again.

Closes: #11926

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Author Checklist

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I have...

• included the correct type prefix in the PR title
• added ! to the type prefix if API or client breaking change
• targeted the correct branch (see PR Targeting)
• provided a link to the relevant issue or specification
• followed the guidelines for building modules
• included the necessary unit and integration tests
• added a changelog entry to CHANGELOG.md
• included comments for documenting Go code
• updated the relevant documentation or specification
• reviewed "Files changed" and left comments if necessary
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I have...

• confirmed the correct type prefix in the PR title
• confirmed ! in the type prefix if API or client breaking change
• confirmed all author checklist items have been addressed
• reviewed state machine logic
• reviewed API design and naming
• reviewed documentation is accurate
• reviewed tests and test coverage
• manually tested (if applicable)

[codecov]

Codecov Report

Merging #11927 (2b0e99b) into main (90272e3) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main   #11927      +/-   ##
==========================================
- Coverage   66.02%   66.01%   -0.01%     
==========================================
  Files         676      675       -1     
  Lines       71346    71273      -73     
==========================================
- Hits        47105    47054      -51     
+ Misses      21559    21539      -20     
+ Partials     2682     2680       -2     

Impacted Files	Coverage Δ
x/gov/client/testutil/deposits.go	88.19% <100.00%> (-5.92%)	⬇️
crypto/keys/internal/ecdsa/privkey.go	82.45% <0.00%> (-1.76%)	⬇️
core/appconfig/config.go
x/group/keeper/keeper.go	55.04% <0.00%> (+0.42%)	⬆️
x/distribution/simulation/operations.go	90.27% <0.00%> (+9.72%)	⬆️

[facundomedica]

Closing in favor of #11940