Declare all interfaces each factory implements

[yurishkuro]

Which problem is this PR solving?

• Part of [Bug]: badger as sampling store not work #4963
• Follow up to feat: Add sampling store support to Badger #4834

Description of the changes

• Explicitly declare all interfaces each factory implements
• Move these declarations to the main file for visibility

How was this change tested?

• CI

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (47f39a8) 95.60% compared to head (515a20e) 95.58%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4967      +/-   ##
==========================================
- Coverage   95.60%   95.58%   -0.03%     
==========================================
  Files         317      317              
  Lines       18689    18689              
==========================================
- Hits        17868    17863       -5     
- Misses        659      663       +4     
- Partials      162      163       +1     

Flag	Coverage Δ
cassandra-3.x	25.64% <ø> (ø)
cassandra-4.x	25.64% <ø> (ø)
elasticsearch-5.x	19.91% <ø> (ø)
elasticsearch-6.x	19.90% <ø> (-0.02%)	⬇️
elasticsearch-7.x	20.03% <ø> (-0.02%)	⬇️
elasticsearch-8.x	20.14% <ø> (ø)
grpc-badger	19.55% <ø> (ø)
kafka	14.07% <ø> (ø)
opensearch-1.x	20.03% <ø> (-0.02%)	⬇️
opensearch-2.x	20.05% <ø> (ø)
unittests	93.33% <ø> (-0.03%)	⬇️

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[jkowall]

lgtm!