Simplify CI test coverage and fix flaky tests

[masih]

Combine the workflow jobs for better concurrency group management and UX.

Fix flaky tendermint tests.

[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 20, 2026, 2:47 PM

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 69.62%. Comparing base (aa58397) to head (47dc3cc).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2937       +/-   ##
===========================================
+ Coverage   57.76%   69.62%   +11.86%     
===========================================
  Files        2111       23     -2088     
  Lines      174240     5725   -168515     
===========================================
- Hits       100648     3986    -96662     
+ Misses      64624     1406    -63218     
+ Partials     8968      333     -8635     

Flag	Coverage Δ
sei-chain	69.72% <ø> (+11.99%)	⬆️
sei-db	68.42% <ø> (ø)

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see 2093 files with indirect coverage changes

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