Fix backup producers not initialized

[lferran]

Description

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How was this PR tested?

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[codecov]

Codecov Report

Attention: Patch coverage is 76.92308% with 6 lines in your changes missing coverage. Please review.

Project coverage is 83.85%. Comparing base (284eae1) to head (7ccd7d0).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
nucliadb/src/nucliadb/backups/tasks.py	50.00%	3 Missing ⚠️
nucliadb/src/nucliadb/ingest/service/writer.py	72.72%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2952      +/-   ##
==========================================
- Coverage   83.92%   83.85%   -0.08%     
==========================================
  Files         487      487              
  Lines       35900    35941      +41     
  Branches    10933    10964      +31     
==========================================
+ Hits        30130    30138       +8     
- Misses       5241     5277      +36     
+ Partials      529      526       -3     

Flag	Coverage Δ
nidx	77.53% <ø> (-0.22%)	⬇️
nucliadb	75.53% <76.92%> (-0.01%)	⬇️
nucliadb-reader	42.06% <76.92%> (+0.01%)	⬆️
nucliadb-search	44.99% <34.61%> (-0.02%)	⬇️
nucliadb-standalone	46.19% <76.92%> (+0.01%)	⬆️
nucliadb-train	44.79% <76.92%> (+0.01%)	⬆️
nucliadb_dataset	55.45% <ø> (ø)
nucliadb_models	84.26% <ø> (ø)
nucliadb_sdk	93.01% <ø> (ø)
nucliadb_telemetry	86.53% <ø> (ø)
nucliadb_utils	84.25% <ø> (ø)

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