Change default sampler to Rate Limited Sampler

[rads-1996]

Description

Default Sampler: Rate Limited Sampler
Default Argument: 5.0 traces per second

All SDK Contribution checklist:

• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.

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• Title of the pull request is clear and informative.
• There are a small number of commits, each of which have an informative message. This means that previously merged commits do not appear in the history of the PR. For more information on cleaning up the commits in your PR, see this page.

[Copilot]

Pull request overview

This pull request changes the default sampling behavior for the Azure Monitor OpenTelemetry distribution from ApplicationInsightsSampler with 100% sampling to RateLimitedSampler with 5.0 traces per second. This is a significant behavioral change aimed at reducing telemetry volume and costs for high-traffic applications.

Changes:

• Changed default sampler from ApplicationInsightsSampler (100% sampling) to RateLimitedSampler (5 traces/second)
• Updated configuration logic to prioritize RateLimitedSampler when no explicit sampler is configured
• Updated tests to reflect the new default value of 5.0 traces per second
• Updated documentation and samples to reflect the new default behavior

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 11 comments.

Show a summary per file

File	Description
sdk/monitor/azure-monitor-opentelemetry/azure/monitor/opentelemetry/_configure.py	Swapped priority order in sampler selection - now checks sampling_ratio first, then defaults to traces_per_second with RateLimitedSampler
sdk/monitor/azure-monitor-opentelemetry/azure/monitor/opentelemetry/_utils/configurations.py	Updated default sampling configuration to use 5.0 traces per second for RateLimitedSampler instead of 1.0 for ApplicationInsightsSampler
sdk/monitor/azure-monitor-opentelemetry/tests/utils/test_configurations.py	Updated test assertions to expect traces_per_second=5.0 as the default instead of sampling_ratio=1.0
sdk/monitor/azure-monitor-opentelemetry/samples/tracing/sampling_configurations.py	Updated sample documentation to reflect new default sampler and added code examples (with syntax errors)
sdk/monitor/azure-monitor-opentelemetry/README.md	Updated documentation to describe the new default sampler and added reference link (with typo)
sdk/monitor/azure-monitor-opentelemetry/CHANGELOG.md	Added entry describing the behavioral change (incorrectly categorized as feature instead of breaking change)

[JacksonWeber]

LGTM