Implement peer.service and associated features

[zarirhamza]

peer.service is now a tag that extracts its value from a subset of source tags that are unique per integration.

• Implement peer.service extraction logic in SpanAttributeSchema` Change peer.service logic #2953

• Replace peer.service tag in target integrations that create spans with span.kind:client or span.kind:producer over the old peer.service tag that simply used to reflect span.service Implement peer.service #2943

• Remove all usages of peer.service from integrations that do not meet the above definition Implement peer.service #2943

• Implement remapper for peer.service that allows users to define key:value pairs which remap the value of peer.service to a new remapped value Implement peer.service remapper #2958

• Add DD_TRACE_REMOVE_INTEGRATION_SERVICE_NAMES_ENABLED so that users can enable global service name defaults to DD_SERVICE Adds DD_TRACE_REMOVE_INTEGRATION_SERVICE_NAMES_ENABLED #2907

Needs explicit @delner approval

[codecov-commenter]

Codecov Report

Merging #2982 (a5a717e) into master (d6fcf01) will increase coverage by 0.00%.
The diff coverage is 98.85%.

@@           Coverage Diff            @@
##           master    #2982    +/-   ##
========================================
  Coverage   98.09%   98.10%            
========================================
  Files        1305     1306     +1     
  Lines       72724    73244   +520     
  Branches     3360     3365     +5     
========================================
+ Hits        71336    71853   +517     
- Misses       1388     1391     +3     

Files Changed	Coverage Δ
...atadog/tracing/contrib/active_record/events/sql.rb	97.61% <ø> (-0.16%)	⬇️
...ng/contrib/active_support/cache/instrumentation.rb	86.11% <ø> (+0.39%)	⬆️
lib/datadog/tracing/contrib/ethon/multi_patch.rb	97.91% <ø> (-0.09%)	⬇️
lib/datadog/tracing/contrib/grpc/formatting.rb	98.21% <0.00%> (-1.79%)	⬇️
lib/datadog/tracing/contrib/racecar/event.rb	97.43% <ø> (+2.31%)	⬆️
...dog/tracing/contrib/active_record/multi_db_spec.rb	93.60% <ø> (-0.57%)	⬇️
...tadog/tracing/contrib/active_record/tracer_spec.rb	97.59% <ø> (-0.14%)	⬇️
...c/datadog/tracing/contrib/ethon/easy_patch_spec.rb	100.00% <ø> (ø)
.../datadog/tracing/contrib/ethon/multi_patch_spec.rb	100.00% <ø> (ø)
spec/datadog/tracing/contrib/rails/cache_spec.rb	98.30% <ø> (-0.14%)	⬇️
... and 93 more

... and 1 file with indirect coverage changes

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[GustavoCaso]

I want to clarify that the requested changes are not about the SpanAttributeSchema module discussion 😄 on #2982 (comment)

The request changes is about the missing specs on spec/datadog/core/configuration/option_spec.rb and the addition of env_to_hash

[delner]

@zarirhamza and I talked about our plans for this. We identified there's a little more work to do to make peer.service configurable. This should be in-flight; once its merged in to this branch, I think this will be ready.

[GustavoCaso]

As far as the code, it is LGTM.

@zarirhamza, thanks for adding type :hash support to the core configuration options.

As for the peer.service logic, I can not review if it is complete or not 😄 since I don't know how it should behave. I will defer that to @delner and @zarirhamza

[delner]

Looks good. Thank you for all your hard work @zarirhamza!