fix: suppress expected ErrAggregateVoteExist error logs in gasless metrics

[blindchaser]

Describe your changes and provide context

When gasless metrics are evaluated after tx processing, oracle vote txs return ErrAggregateVoteExist because the vote now exists in state. This change treats ErrAggregateVoteExist as a signal that the tx was a gasless oracle vote and skips gas metrics recording, while still logging other unexpected errors.

Testing performed to validate your change

[github-actions]

The latest Buf updates on your PR. Results from workflow Buf / buf (pull_request).

Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	✅ passed	✅ passed	✅ passed	Feb 5, 2026, 3:23 PM

[codecov]

Codecov Report

❌ Patch coverage is 12.50000% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.60%. Comparing base (bcfab9b) to head (f72b62b).

Files with missing lines	Patch %	Lines
app/app.go	12.50%	5 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2796      +/-   ##
==========================================
- Coverage   56.62%   56.60%   -0.03%     
==========================================
  Files        2031     2031              
  Lines      165929   165935       +6     
==========================================
- Hits        93962    93927      -35     
- Misses      63734    63774      +40     
- Partials     8233     8234       +1     

Flag	Coverage Δ
sei-chain	41.45% <12.50%> (-0.01%)	⬇️
sei-cosmos	48.12% <ø> (+<0.01%)	⬆️
sei-db	68.72% <ø> (ø)
sei-tendermint	58.07% <ø> (-0.08%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
app/app.go	65.85% <12.50%> (-0.22%)	⬇️

... and 23 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.