[WIP] Remove numBuckets argument from CreateSamplingStore() API

[yurishkuro]

Which problem is this PR solving?

• CreateSamplingStore() used to require numBuckets argument. However, only memory storage was dependent on this arg. This creates an unnecessary coupling in adaptive sampling between aggregator and provider.

Description of the changes

• Move memory config into the same package as the factory (similar to other backends)
• Add a config param for numBuckets for sampling (unique to memstore)
• Builds on top of Rename strategy store to sampling strategy provider #5634

How was this change tested?

• CI

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.22%. Comparing base (d8185ac) to head (b6c45b8).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5635      +/-   ##
==========================================
+ Coverage   96.20%   96.22%   +0.02%     
==========================================
  Files         327      326       -1     
  Lines       16014    16009       -5     
==========================================
- Hits        15406    15405       -1     
+ Misses        432      427       -5     
- Partials      176      177       +1     

Flag	Coverage Δ
badger_v1	8.05% <6.25%> (-0.01%)	⬇️
badger_v2	1.93% <0.00%> (-0.01%)	⬇️
cassandra-3.x-v1	16.44% <6.25%> (-0.01%)	⬇️
cassandra-3.x-v2	1.85% <0.00%> (-0.01%)	⬇️
cassandra-4.x-v1	16.44% <6.25%> (-0.01%)	⬇️
cassandra-4.x-v2	1.85% <0.00%> (-0.01%)	⬇️
elasticsearch-7.x-v1	18.89% <6.25%> (-0.01%)	⬇️
elasticsearch-8.x-v1	19.07% <6.25%> (-0.01%)	⬇️
elasticsearch-8.x-v2	19.07% <6.25%> (-0.02%)	⬇️
grpc_v1	9.50% <56.25%> (+0.02%)	⬆️
grpc_v2	7.57% <50.00%> (+0.03%)	⬆️
kafka	9.77% <25.00%> (-0.01%)	⬇️
opensearch-1.x-v1	18.92% <6.25%> (-0.01%)	⬇️
opensearch-2.x-v1	18.93% <6.25%> (+<0.01%)	⬆️
opensearch-2.x-v2	18.92% <6.25%> (-0.02%)	⬇️
unittests	94.10% <94.73%> (+0.02%)	⬆️

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