RUM-1556: Update default propagation style from Datadog to Datadog+TraceContext

[0xnm]

What does this PR do?

This is Android counterpart of DataDog/dd-sdk-ios#1529

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

Merging #1696 (46f06cb) into develop (43c2c3e) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop    #1696      +/-   ##
===========================================
- Coverage    83.53%   83.52%   -0.01%     
===========================================
  Files          465      465              
  Lines        16025    16030       +5     
  Branches      2376     2375       -1     
===========================================
+ Hits         13385    13388       +3     
- Misses        1999     2003       +4     
+ Partials       641      639       -2     

Files	Coverage Δ
...atadog/android/core/configuration/Configuration.kt	96.51% <100.00%> (+0.13%)	⬆️
...nal/net/DefaultFirstPartyHostHeaderTypeResolver.kt	90.48% <100.00%> (+1.00%)	⬆️
.../kotlin/com/datadog/android/trace/AndroidTracer.kt	96.30% <100.00%> (+1.06%)	⬆️
...n/com/datadog/android/okhttp/DatadogInterceptor.kt	72.54% <100.00%> (+0.59%)	⬆️
...datadog/android/okhttp/trace/TracingInterceptor.kt	81.67% <100.00%> (+1.03%)	⬆️

... and 21 files with indirect coverage changes