RUM-17613: timeseries [3/5] Pass the live RUM context to timeseries pipelines

[satween]

What does this PR do?

Timeseries batches carried the RumContext captured when RumSessionScope created the collector, so every event was attributed to whatever view happened to be active at session start. The collector now tracks the context and hands it to Pipeline.execute() / Pipeline.flush() per call, and RumSessionScope feeds it the active context on every handled event.

Pipeline takes over its own synchronization as part of that: reader.read() stays outside the lock, so a concurrent flush() waits only for the buffer and never for /proc I/O.

The sampling lifecycle is unchanged here — background suspension still behaves exactly as before, gated on TimeseriesConfiguration.collectInBackground. [4/5] reworks it.

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)

Ref: RUM-17613

[datadog-datadog-prod-us1-2]

🎉 All green!

🧪 All tests passed
❄️ No new flaky tests detected

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 72.82% (+0.00%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 340e8c5 | Docs | Datadog PR Page | Give us feedback!}

[codecov-commenter]

Codecov Report

❌ Patch coverage is 95.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 73.37%. Comparing base (a31ef2f) to head (340e8c5).

Files with missing lines	Patch %	Lines
.../internal/timeseries/DefaultTimeseriesCollector.kt	87.50%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@                  Coverage Diff                   @@
##           feature/timeseries    #3717      +/-   ##
======================================================
+ Coverage               73.34%   73.37%   +0.03%     
======================================================
  Files                    1012     1012              
  Lines                   37027    37029       +2     
  Branches                 6381     6380       -1     
======================================================
+ Hits                    27154    27167      +13     
+ Misses                   8046     8041       -5     
+ Partials                 1827     1821       -6     

Files with missing lines	Coverage Δ
...droid/rum/internal/domain/scope/RumSessionScope.kt	93.26% <100.00%> (+0.04%)	⬆️
...al/timeseries/DefaultTimeseriesCollectorFactory.kt	100.00% <100.00%> (ø)
...atadog/android/rum/internal/timeseries/Pipeline.kt	96.88% <100.00%> (+0.10%)	⬆️
.../internal/timeseries/DefaultTimeseriesCollector.kt	76.00% <87.50%> (-1.55%)	⬇️

... and 43 files with indirect coverage changes

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[satween]

• RUM-17613: timeseries [5/5] Add integration tests for timeseries collection #3718
• RUM-17613: timeseries [4/5] Flush the batch in background #3719
• RUM-17613: timeseries [3/5] Pass the live RUM context to timeseries pipelines #3717 👈 (View in Graphite)
• RUM-17613: timeseries [2/5] Using updated timeseries schema from rum_event_schema #3712 : 1 other dependent PR (#3713 )
• feature/timeseries

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