Update opentelemetry-dotnet monorepo to 1.15.3

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
OpenTelemetry.Exporter.OpenTelemetryProtocol (source)	1.14.0 → 1.15.3
OpenTelemetry.Extensions.Hosting (source)	1.14.0 → 1.15.3

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Release Notes

open-telemetry/opentelemetry-dotnet (OpenTelemetry.Exporter.OpenTelemetryProtocol)

v1.15.3

Release details: 1.15.3

• Breaking change: Fixed tracestate parsing to reject keys that do not
  begin with a lowercase letter, including keys beginning with digits, to
  align with the W3C Trace Context specification.
• Breaking change: Fixed an insecure disk retry default for OTLP export.
  Disk retry now requires OTEL_DOTNET_EXPERIMENTAL_OTLP_DISK_RETRY_DIRECTORY_PATH
  when OTEL_DOTNET_EXPERIMENTAL_OTLP_RETRY=disk is configured.
• Improve efficiency of parsing of baggage and B3 propagation headers.
• OtlpLogExporter now uses IHttpClientFactory on .NET 8+.
• Fixed an issue in OTLP/gRPC retry handling when parsing gRPC statuses.
• Fixed OTEL_SPAN_ATTRIBUTE_VALUE_LENGTH_LIMIT not being applied.
• Fixed baggage and trace headers not respecting the maximum length in some cases.
• Fixed BaggagePropagator to trim optional whitespace (OWS) around =
  separators when parsing the baggage header.
• Fixed BaggagePropagator to strip baggage properties from values when
  parsing the baggage header.
• Fixed OTLP persistent storage clean-up handling for malformed filenames.
• Fixed resource leak in batch and periodic exporting task workers for Blazor/WASM.
• Fixed LogRecord.LogLevel to preserve LogLevel.None.
• Fixed OTEL_TRACES_SAMPLER_ARG handling for out-of-range values.
• Fixed an issue with OTLP disk retry storage where metrics and logs used the
  traces storage directory.
• Fixed full OTLP endpoint being logged by internal diagnostics.
• Improve efficiency of parsing of baggage, B3 and Jaeger propagation headers.
• Hardened Zipkin exporter memory usage for endpoint caching and array tag
  serialization.

v1.15.2

Release details: 1.15.2

• Limit how much of the response body is read by the OTLP exporter when
  export fails and error logging is enabled.
• Added Task-based worker support for BatchExportProcessor and
  PeriodicExportingMetricReader to enable the OpenTelemetry SDK to work
  in single-threaded WebAssembly environments such as Blazor and
  Uno Platform.

v1.15.1

Release details: 1.15.1

• Breaking change: The Baggage API now disallows empty baggage names and
  treats baggage names and values as case sensitive, aligning with the latest
  Baggage API specification.
• Various bug fixes across OpenTelemetry.Api and OpenTelemetry SDK,
  including fixes for thread-safety, sampler edge cases, metrics precision,
  and observable instrument lifecycle handling.

v1.15.0

Release details: 1.15.0

• Added support for ActivitySource.TelemetrySchemaUrl
  and Meter.TelemetrySchemaUrl properties across exporters.
• Improved performance and reduced memory consumption for metrics histograms.
• Added mTLS configuration support for the OTLP exporter (client cert/key and
  CA certificate options).
• OpenTelemetry.Exporter.Zipkin is deprecated and will stop receiving updates
  in December 2026. Zipkin already supports OTLP ingestion.
  Migrate to OpenTelemetry.Exporter.OpenTelemetryProtocol as stated
  in the Deprecating Zipkin Exporter blog post.

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