[exporter/loki] Add default labels job=service.namespace/service.name, instance=service.instance.id

[mar4uk]

Component(s)

exporter/loki

Is your feature request related to a problem? Please describe.

Currently, the loki exporter set only one label by default: exporter=OTLP.
This label is not enough to correlate logs in Loki with Prometheus metrics.

Describe the solution you'd like

To correlate logs in Loki with Prometheus metrics at least two labels are needed: job=service.namespace/service.name and instance=service.instance.id.
Adding default essential labels will simplify configuration and allow correlation between logs and metrics out of the box

Describe alternatives you've considered

Users can set these labels manually via a resource processor

Additional context

No response

[mar4uk]

fixed in #18499