Draft: Observability helper banner for traces and metrics views

What does this MR do and why?

NOTE: The design for this banner is still in review.

Adds an observability helper banner so users can easily view OTEL HTTP configration for their project. This endpoint URL is dynamic, based on the current namespace and project id, so it's useful to have it here.

Related to gitlab-org/opstrace/opstrace#2505

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