chore: minor processor cleanup

[Sidddddarth]

Description

Cleaned up some processor code.
Specifically the usage of 2 flags(trackingPlanEnabled and userTransformationEnabled) to decide the PU and inPU at various stages during the computation of metrics.
Also using stage literals from one package(utils/types) instead of two earlier(processor/transformer and utils/types).

Linear Ticket

< Replace with Linear Link >

Security

• The code changed/added as part of this pull request won't create any security issues with how the software is being used.

[codecov]

Codecov Report

Attention: 134 lines in your changes are missing coverage. Please review.

Comparison is base (b80d273) 71.53% compared to head (988ff9a) 71.74%.
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3876      +/-   ##
==========================================
+ Coverage   71.53%   71.74%   +0.20%     
==========================================
  Files         373      373              
  Lines       54826    54891      +65     
==========================================
+ Hits        39219    39379     +160     
+ Misses      13272    13190      -82     
+ Partials     2335     2322      -13     

Files	Coverage Δ
processor/trackingplan.go	95.45% <100.00%> (ø)
processor/transformer/transformer.go	90.79% <100.00%> (ø)
warehouse/api/http.go	78.94% <100.00%> (ø)
warehouse/app.go	89.59% <100.00%> (ø)
warehouse/integrations/testhelper/setup.go	99.68% <100.00%> (ø)
warehouse/internal/model/upload.go	100.00% <ø> (ø)
warehouse/integrations/testhelper/verify.go	89.64% <91.66%> (ø)
warehouse/internal/model/source.go	91.66% <91.66%> (ø)
warehouse/slave/worker.go	81.74% <76.19%> (-0.88%)	⬇️
warehouse/internal/repo/table_upload.go	91.69% <90.69%> (+0.13%)	⬆️
... and 4 more

... and 10 files with indirect coverage changes

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[atzoum]

@Sidddddarth how do we verify no regression has been introduced?

[atzoum]

• transformer.EventFilterStage is unused
• transformer.TrackingPlanValidationStage is being used by processor_test.go

It might be best to unexport stage constants, since they appear to be for internal use only:

• userTransformerStage
• destTransformerStage
• trackingPlanValidationStage

[Sidddddarth]

@Sidddddarth how do we verify no regression has been introduced?

adding some coverage here

[atzoum]

Please add a description of the changes, helpful to the review process

[atzoum]

@Sidddddarth how do we verify no regression has been introduced?

adding some coverage here

why is it on a separate PR?

[Sidddddarth]

@Sidddddarth how do we verify no regression has been introduced?

adding some coverage here

why is it on a separate PR?

That started when there were no tests for reporting at all. Considering we have some now, they're of no use anymore.
And I did it in another PR so we could have assertions in place before I change code that is heavily involved in the pipeline.
Closing that PR now.