Block readers from starting during initial replication

[javitonino]

Description

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How was this PR tested?

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.28%. Comparing base (ae2ae0c) to head (4f33306).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2484   +/-   ##
=======================================
  Coverage   86.28%   86.28%           
=======================================
  Files         375      375           
  Lines       23381    23381           
=======================================
  Hits        20174    20174           
  Misses       3207     3207           

Flag	Coverage Δ
nucliadb	74.06% <ø> (ø)
nucliadb-ingest	29.10% <ø> (ø)
nucliadb-reader	25.03% <ø> (ø)
nucliadb-search	37.23% <ø> (ø)
nucliadb-standalone	47.02% <ø> (ø)
nucliadb-train	45.65% <ø> (ø)
nucliadb-writer	39.97% <ø> (ø)
nucliadb_dataset	55.31% <ø> (ø)
nucliadb_models	85.13% <ø> (ø)
nucliadb_sdk	80.11% <ø> (ø)
nucliadb_sidecar	89.03% <ø> (ø)
nucliadb_telemetry	86.55% <ø> (ø)
nucliadb_utils	84.01% <ø> (ø)

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