Migrate tracing to OpenTelemetry and add support for standard OTel env config

[colega]

This migrates this app to use OpenTelemetry tracing library instead of OpenTracing, which has been deprecated for a while.

The app will now support standard 'OTEL_' environment variables as per OTel SDK docs, and the exposition in OTLP protocol.

[Copilot]

Pull Request Overview

This PR migrates the app’s tracing implementation from OpenTracing to OpenTelemetry while adding support for standard OTEL environment variables.

• Replace OpenTracing calls with OpenTelemetry invocations.
• Update HTTP transport instrumentation and environment variables in deployment manifests.
• Adjust dependency management in go.mod to include new OTel packages.

Reviewed Changes

Copilot reviewed 25 out of 25 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
pkg/instrumentation/kubernetes_api_client.go	Switches HTTP transport instrumentation to OpenTelemetry.
pkg/controller/controller.go	Replaces OpenTracing span with OpenTelemetry tracer in reconcile.
pkg/admission/zone_tracker.go	Updates tracing for config map operations using OpenTelemetry tracer.
pkg/admission/prep_downscale.go	Migrates several OpenTracing spans to OpenTelemetry spans.
pkg/admission/no_downscale.go	Introduces an OpenTelemetry tracer for the admission package.
go.mod	Updates dependencies to include OpenTelemetry libraries.
development/rollout-operator-deployment.yaml	Updates environment variables to support OTEL endpoints.
development/jaeger-service.yaml	Removes Jaeger UDP port and adds OTLP HTTP endpoint.
cmd/rollout-operator/main.go	Adapts service name configuration and initializes tracing accordingly.
CHANGELOG.md	Documents the migration to OpenTelemetry.

Comments suppressed due to low confidence (1)

go.mod:9

• [nitpick] Although the migration replaces direct OpenTracing calls, the opentracing dependencies are still present as indirect dependencies. If they are no longer needed, consider removing them to reduce dependency clutter.

	github.com/grafana/dskit v0.0.0-20250611075409-46f51e1ce914

[colega]

Note for reviewers: jaeger also supports otlp, and I didn't replace it with something else because having something that has a frontend to query comes in handy in this dev env.