ci: Make build-fuzz failures fatal now that upstream is fixed

[kostko]

Fix #3374

[codecov]

Codecov Report

Merging #3521 (8f5587a) into master (c237102) will decrease coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #3521      +/-   ##
==========================================
- Coverage   66.41%   66.36%   -0.05%     
==========================================
  Files         373      373              
  Lines       33956    33956              
==========================================
- Hits        22551    22536      -15     
- Misses       8120     8151      +31     
+ Partials     3285     3269      -16     

Impacted Files	Coverage Δ
...ensus/tendermint/apps/staking/state/accumulator.go	62.06% <0.00%> (-6.90%)	⬇️
go/staking/api/grpc.go	52.75% <0.00%> (-5.52%)	⬇️
go/consensus/tendermint/apps/staking/query.go	35.71% <0.00%> (-4.77%)	⬇️
go/storage/mkvs/tree.go	86.95% <0.00%> (-4.35%)	⬇️
go/worker/storage/service_external.go	48.14% <0.00%> (-3.71%)	⬇️
...n/crypto/signature/signers/memory/memory_signer.go	72.41% <0.00%> (-3.45%)	⬇️
go/storage/api/root_cache.go	75.00% <0.00%> (-3.34%)	⬇️
go/worker/storage/committee/checkpoint_sync.go	71.98% <0.00%> (-2.73%)	⬇️
go/storage/database/database.go	65.88% <0.00%> (-2.36%)	⬇️
go/consensus/tendermint/staking/staking.go	54.02% <0.00%> (-2.30%)	⬇️
... and 18 more

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