Change ApplicationInsights InstrumentationKey to ConnectionString

[fabistb]

What content needs to be created or modified?
Microsoft has announced the support stop for the application insights instrumentation key. While from March 31 2025 the ingestion will continue to work the support will stop.

Besides this the connection string provides additional features and is the recommended solution.

Describe the solution you'd like
Change the Using OpenTelemetry Collector to collect traces to send to App Insights documentation from Instrumentation Key to connection string.

Adjust the otel collector example:

exporters:
  azuremonitor:
    connection_string: ""

Where should the new material be placed?
https://docs.dapr.io/operations/observability/tracing/otel-collector/open-telemetry-collector-appinsights/

https://github.com/dapr/docs/blob/v1.15/daprdocs/static/docs/open-telemetry-collector/open-telemetry-collector-appinsights.yaml

Additional context
https://learn.microsoft.com/en-us/azure/azure-monitor/app/connection-strings

https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/release/v0.101.x/exporter/azuremonitorexporter/README.md

[fabistb]

/assign

[msfussell]

Issue resolved