[service/internal/graph] Add size throughput metrics

[djaglowski]

Follows #12812

This PR adds the size metrics defined in the Pipeline Component Telemetry RFC.

[djaglowski]

cc @codeboten @mx-psi

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.59%. Comparing base (e9f3dec) to head (ff7fd74).
Report is 19 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #13032      +/-   ##
==========================================
+ Coverage   91.53%   91.59%   +0.05%     
==========================================
  Files         504      505       +1     
  Lines       28154    28326     +172     
==========================================
+ Hits        25772    25944     +172     
  Misses       1873     1873              
  Partials      509      509              

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[mx-psi]

cc @open-telemetry/collector-approvers I will merge this next Tuesday unless somebody objects before then

[jade-guiton-dd]

I'm a bit confused about how these metrics are supposed to be enabled/disabled, see comments.

If the intent is to enable these metrics based on verbosity level like we do for the byte-based metrics in the batch processor, shouldn't there be a change in configureViews in service/service.go?

Concerns raised by Jade are valid

[djaglowski]

If the intent is to enable these metrics based on verbosity level like we do for the byte-based metrics in the batch processor, shouldn't there be a change in configureViews in service/service.go?

My concern is only that these metrics exist and can be enabled by users. I will update the PR to follow the pattern used by the byte-based metrics in batch processor.

[jade-guiton-dd]

LGTM

[mx-psi]

@dmitryax I am going to merge this since the unit tests show that the counter is not incremented when enabled is false and all the Size calls are guarded with checks to isEnabled. If you find anything that looks wrong I can take over if Dan is no longer around