RUM-16325 timeseries: Post-review fixes for timeseries

[satween]

What does this PR do?

Applies post-review fixes from PR on top of the schema update: adjustments to RumFeature, RumSessionScope, TimeseriesConfiguration, and the CPU/Memory event serializers, plus added/updated unit and end-to-end tests.

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

❌ Patch coverage is 80.95238% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 72.61%. Comparing base (cba54e4) to head (34c8284).

Files with missing lines	Patch %	Lines
...lin/com/datadog/android/rum/internal/RumFeature.kt	66.67%	2 Missing ⚠️
...droid/rum/internal/domain/scope/RumSessionScope.kt	87.50%	0 Missing and 1 partial ⚠️
.../android/rum/timeseries/TimeseriesConfiguration.kt	66.67%	1 Missing ⚠️

Additional details and impacted files

@@                  Coverage Diff                   @@
##           feature/timeseries    #3556      +/-   ##
======================================================
+ Coverage               72.60%   72.61%   +0.01%     
======================================================
  Files                     980      980              
  Lines                   36053    36058       +5     
  Branches                 6033     6031       -2     
======================================================
+ Hits                    26174    26182       +8     
  Misses                   8198     8198              
+ Partials                 1681     1678       -3     

Files with missing lines	Coverage Δ
...kotlin/com/datadog/android/rum/RumConfiguration.kt	92.47% <ø> (ø)
.../android/rum/internal/monitor/DatadogRumMonitor.kt	86.20% <ø> (ø)
...ternal/timeseries/serializer/CpuEventSerializer.kt	90.38% <100.00%> (+3.85%)	⬆️
...nal/timeseries/serializer/MemoryEventSerializer.kt	91.23% <100.00%> (+3.51%)	⬆️
...droid/rum/internal/domain/scope/RumSessionScope.kt	92.05% <87.50%> (+0.23%)	⬆️
.../android/rum/timeseries/TimeseriesConfiguration.kt	90.91% <66.67%> (ø)
...lin/com/datadog/android/rum/internal/RumFeature.kt	90.82% <66.67%> (-1.02%)	⬇️

... and 31 files with indirect coverage changes

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The base branch was changed.

[hamorillo]

LGTM!

nit: Not related to this PR but as you are modifying this file maybe you can add the @Test missing in line:

dd-sdk-android/features/dd-sdk-android-rum/src/test/kotlin/com/datadog/android/rum/internal/domain/scope/RumSessionScopeTest.kt

Line 367 in 0d7a259

fun `M return scope from handleEvent W stopped { with active child scopes }`() {