RUM-6850: Add more precision to Effective Sample Rate

[simaoseica-dd]

What and why?

It aligns the telemetry schema with the updates done on the Effective Sample Rate PR.
Effective Sample Rate has now support for floating points.

How?

By updating the RUMDataModels and the associated tests.

Review checklist

• Feature or bugfix MUST have appropriate tests (unit, integration)
• Make sure each commit and the PR mention the Issue number or JIRA reference
• Add CHANGELOG entry for user facing changes
• Add Objective-C interface for public APIs (see our guidelines [internal]) and run make api-surface)

[datadog-datadog-prod-us1]

Datadog Report

Branch report: simaoseica/RUM-6850/add-more-precision-to-effective-sample-rate
Commit report: 6c9ac6a
Test service: dd-sdk-ios

✅ 0 Failed, 772 Passed, 2819 Skipped, 36.94s Total duration (1m 54.28s time saved)

[ncreated]

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