Fix queue populator shared metrics

[Kerkesni]

• Queue Populator can be used for a single or multiple extensions at once. Currently the 'origin' label in the metrics is always set to "replication" which is not always true, we change this to make it hold the list of loaded extensions in the current queue populator instance.
• Some queue populator metrics are shared between all extensions and not specific to replication. We change their prefix to s3_backbeat_populator instead of s3_replication

Issue: BB-527

[bert-e]

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[bert-e]

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[codecov]

Codecov Report

Attention: Patch coverage is 88.88889% with 1 line in your changes missing coverage. Please review.

Project coverage is 71.39%. Comparing base (287b942) to head (b2eeb64).

Files with missing lines	Patch %	Lines
lib/queuePopulator/QueuePopulator.js	0.00%	1 Missing ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
lib/queuePopulator/BucketFileLogReader.js	60.00% <100.00%> (+38.94%)	⬆️
lib/queuePopulator/KafkaLogReader.js	64.70% <100.00%> (+45.95%)	⬆️
lib/queuePopulator/MongoLogReader.js	64.70% <100.00%> (+39.70%)	⬆️
lib/queuePopulator/RaftLogReader.js	88.88% <100.00%> (+59.47%)	⬆️
lib/queuePopulator/QueuePopulator.js	35.11% <0.00%> (-0.45%)	⬇️

... and 2 files with indirect coverage changes

Components	Coverage Δ
Bucket Notification	75.37% <ø> (ø)
Core Library	76.41% <88.88%> (+0.66%)	⬆️
Ingestion	69.24% <ø> (ø)
Lifecycle	76.14% <ø> (ø)
Oplog Populator	85.06% <ø> (ø)
Replication	57.79% <ø> (ø)
Bucket Scanner	85.60% <ø> (ø)

@@                 Coverage Diff                 @@
##           development/9.0    #2612      +/-   ##
===================================================
+ Coverage            71.11%   71.39%   +0.27%     
===================================================
  Files                  201      201              
  Lines                13334    13338       +4     
===================================================
+ Hits                  9483     9522      +39     
+ Misses                3841     3806      -35     
  Partials                10       10              

Flag	Coverage Δ
api:retry	9.52% <0.00%> (-0.01%)	⬇️
api:routes	9.33% <0.00%> (-0.01%)	⬇️
bucket-scanner	85.60% <ø> (ø)
ingestion	12.28% <0.00%> (-0.01%)	⬇️
lib	7.36% <0.00%> (-0.01%)	⬇️
lifecycle	18.81% <0.00%> (-0.01%)	⬇️
notification	1.07% <0.00%> (-0.01%)	⬇️
replication	18.62% <0.00%> (+0.03%)	⬆️
unit	48.38% <88.88%> (+0.23%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

[francoisferrand]

not needed, please rebase...

[francoisferrand]

should we not "join" the strings in the array? (here or maybe better in the constructor)

this._extensionNames.join(',')

[francoisferrand]

it would be nice to document somewhere what "origin" really is : i.e. not the pod/process which generated the metric, but the kind of workflow/process from which the 'processing' was triggered... (i.e. so that we have replication count either from "replication" rules and "transition")