Update opentelemetry-dotnet monorepo to 1.15.1

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
OpenTelemetry.Exporter.OpenTelemetryProtocol (source)	1.12.0 → 1.15.1
OpenTelemetry.Extensions.Hosting (source)	1.12.0 → 1.15.1

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Release Notes

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

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.

v1.14.0

Release details: 1.14.0

• Add support for .NET 10.0.
• Breaking Change When targeting net8.0, the package now depends on version
  8.0.0 of the Microsoft.Extensions.DependencyInjection.Abstractions,
  Microsoft.Extensions.Diagnostics.Abstractions,
  Microsoft.Extensions.Hosting.Abstractions and
  Microsoft.Extensions.Logging.Configuration NuGet packages.
• Update System.Diagnostics.DiagnosticSource dependency to 10.0.0
  for all target frameworks.
• Update Microsoft.Extensions.* dependencies to 10.0.0
  for .NET Framework and .NET Standard.
• Breaking Change NuGet packages now use the Sigstore bundle format
  (.sigstore.json) for digital signatures instead of separate signature
  (.sig) and certificate (.pem) files. This requires cosign 3.0 or later
  for verification. See the Digital signing
  section for updated verification instructions.

v1.13.1

Release details: 1.13.1

• In version 1.13.0, the digital signature (.dll-keyless.sig) and
  certificate (.dll-keyless.pem) files were unintentionally omitted from the
  published NuGet packages.
• This hotfix restores the Sigstore signing artifacts for all target frameworks
  (net462, netstandard2.0, netstandard2.1, net8.0, net9.0), ensuring
  the integrity of DLL verification using Sigstore cosign.

v1.13.0

Release details: 1.13.0

• gRPC calls to export traces, logs, and metrics using OtlpExportProtocol.Grpc
  now set the TE=trailers HTTP request header to improve interoperability.
• EventName is now exported by default as EventName instead of
  logrecord.event.name when specified through ILogger or the experimental
  log bridge API.

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