RUM-8051: Implement Head-based sampling for network instrumentation

[0xnm]

What does this PR do?

This PR implements Head-based sampling for the network instrumentation to align with default sampling existing in other Datadog tracers.

In short, Head-based sampling (HBS) allows to have a single sampling decision for the whole trace: it is kept or dropped, instead of the individual spans.

This also aligns with the following changes in iOS SDK done in the past:

• RUM-3470 feat: Head-based sampling for local and (automatic) distributed tracing dd-sdk-ios#1783
• RUM-3470 feat: Head-based sampling for manual distributed tracing dd-sdk-ios#1793
• RUM-3470 feat: Head-based sampling dd-sdk-ios#1794

Now, if there is a parent span (propagated through the headers or via request tag; OpenTracing or OpenTelemetry), then its sampling decision will be taken into account instead of the sampling decision made by the network instrumentation.

If there is no parent tracing context for the incoming request, then sampling decision will be made by interceptor.

The necessary integration tests are added, they uncovered some issues we had with trace propagation.

Also this PR bring the following change: spans with DROP sampling decision are not written, they are rejected by the intake anyway, so it makes no sense to send them.

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Make sure you discussed the feature or bugfix with the maintaining team in an Issue
• Make sure each commit and the PR mention the Issue number (cf the CONTRIBUTING doc)

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 57.53425% with 31 lines in your changes missing coverage. Please review.

Project coverage is 70.01%. Comparing base (eebc972) to head (8852339).
Report is 2 commits behind head on develop.

Files with missing lines	Patch %	Lines
...datadog/android/okhttp/trace/TracingInterceptor.kt	53.06%	18 Missing and 5 partials ⚠️
...otlin/com/datadog/android/okhttp/otel/OkHttpExt.kt	22.22%	5 Missing and 2 partials ⚠️
...adog/opentracing/propagation/DatadogHttpCodec.java	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2483      +/-   ##
===========================================
+ Coverage    69.92%   70.01%   +0.09%     
===========================================
  Files          788      788              
  Lines        29604    29647      +43     
  Branches      4944     4961      +17     
===========================================
+ Hits         20698    20756      +58     
+ Misses        7527     7520       -7     
+ Partials      1379     1371       -8     

Files with missing lines	Coverage Δ
...cy/trace/common/sampling/RateByServiceSampler.java	60.87% <100.00%> (ø)
...dog/android/trace/internal/data/OtelTraceWriter.kt	89.66% <100.00%> (+1.19%)	⬆️
...datadog/android/trace/internal/data/TraceWriter.kt	93.75% <100.00%> (+0.65%)	⬆️
...adog/opentracing/propagation/DatadogHttpCodec.java	83.33% <50.00%> (-1.17%)	⬇️
...otlin/com/datadog/android/okhttp/otel/OkHttpExt.kt	30.00% <22.22%> (-45.00%)	⬇️
...datadog/android/okhttp/trace/TracingInterceptor.kt	75.21% <53.06%> (-1.80%)	⬇️

... and 32 files with indirect coverage changes