Observability Configuration Phase 2: Set OTLP Collector for all components

[david-martin]

Currently, if using tracing, the OTLP collector needs to be configured in multiple places (istio, limitador, authorino) as per https://docs.kuadrant.io/dev/kuadrant-operator/doc/observability/tracing/

Expose the collector url in the spec of the Kuadrant CR, like this:

observability:
  otlp_collector: rpc://temp:6379

The kuadrant operator should set all configuration points of components to use the configured collector.
As part of this work, update the docs guide to reflect how to enable tracing using this new configuration.