[fix][backend]auto_task:fix count ttl & delete useless log

[zero3233-bd]

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[CozeLoop]

Submitted one inline comment; please consider clamping TTL to non-negative to avoid premature expiration.

[codecov]

Codecov Report

❌ Patch coverage is 25.00000% with 6 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
backend/modules/observability/infra/repo/task.go	0.00%	6 Missing ⚠️

❌ Your patch status has failed because the patch coverage (25.00%) is below the target coverage (80.00%). You can increase the patch coverage or adjust the target coverage.

@@            Coverage Diff             @@
##             main     #307      +/-   ##
==========================================
- Coverage   68.48%   68.47%   -0.01%     
==========================================
  Files         569      569              
  Lines       51742    51739       -3     
==========================================
- Hits        35433    35430       -3     
  Misses      13563    13563              
  Partials     2746     2746              

Flag	Coverage Δ
unittests	68.47% <25.00%> (-0.01%)	⬇️

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Files with missing lines	Coverage Δ
...d/modules/observability/domain/task/entity/task.go	55.55% <100.00%> (-2.34%)	⬇️
...domain/task/service/taskexe/tracehub/subscriber.go	71.55% <ø> (-0.25%)	⬇️
backend/modules/observability/infra/repo/task.go	26.69% <0.00%> (ø)

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