Update opentelemetry-dotnet monorepo to 1.15.0

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
OpenTelemetry.Exporter.OpenTelemetryProtocol (source)	1.14.0 → 1.15.0
OpenTelemetry.Extensions.Hosting (source)	1.14.0 → 1.15.0

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Release Notes

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

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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Configuration

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