feat: autoscaling for telemetry gateways (new centralized OTLPGateway architecture)

[TeodorSAP]

Description

Warning

• This is a feature branch PR. Changes made to the GitHub workflow need to be reverted before merging.
• This feature branch has been created from main on the 25th of February 2026 at commit 3378a828cc6c591b225e6893c3771f02df65b86e. Please ensure every feature since then is reviewed thoroughly and properly implemented/adapted to this branch's refactoring
• This PR is comprised of the following sub-PRs:
  • feat: implement OTLPGateway Controller and ConfigMap and remove current TraceGateway and LogGateway logic #3025
  • feat: refactor MetricGateway to centralized OTLPGateway architecture #3127
  • chore: leftovers for centralized OTLPGateway refactoring #3311

Changes proposed in this pull request (what was done and why):

• Introduce new OTLPGateway ConfigMap (valid pipelines syncer)
• Introduce new OTLPGateway Controller that watches the OTLPGateway ConfigMap
• Merge Logs, Metrics, and Traces Metrics Services into a single OTLP Gateway Metrics Service
• Traces:
  • Refactor TracePipeline controller to exclusively watch and validate TracePipeline CRs and write valid TracePipeline references into the OTLPGateway ConfigMap
  • Remove TraceGateway logic
  • Adapt codebase and tests accordingly
• Logs:
  • Remove deployOTLPGateway feature flag logic introduced in: feat: add support for the daemonset for gateways #2926
  • Refactor LogPipeline controller to exclusively watch and validate LogPipeline CRs and write valid LogPipeline references into the OTLPGateway ConfigMap
  • Remove LogGateway logic
  • Adapt codebase and tests accordingly
• Metrics:
  • Merge Metrics Metrics Service into a single OTLP Gateway Metrics Service
  • Refactor MetricPipeline controller to exclusively watch and validate MetricPipeline CRs and write valid MetricPipeline references into the OTLPGateway ConfigMap
  • Remove old MetricGateway logic
  • Adapt codebase and tests accordingly

Changes refer to particular issues, PRs or documents:

• Autoscaling for telemetry gateways #424

Traceability

• The PR is linked to a GitHub issue.
• The follow-up issues (if any) are linked in the Related Issues section.
• If the change is user-facing, the documentation has been adjusted.
• If a CRD is changed, the corresponding Busola ConfigMap has been adjusted.
• The feature is unit-tested.
• The feature is e2e-tested.