Update usage of sidecar.istio.io/inject to reflect change from annotation to label

[saga-dash]

Hi team,

As per the following Istio API change:
istio/api#2486
https://istio.io/v1.15/docs/reference/config/annotations/

The sidecar.istio.io/inject field has been transitioned from an annotation to a label. This change means that existing configurations or filters relying on the annotation format may no longer function as expected in environments using newer versions of Istio.

Searching this repo reveals usage of the annotation form:
https://github.com/search?q=repo%3Asignalfx%2Fsplunk-otel-collector-chart+sidecar.istio.io%2Finject&type=code

Could we please update any relevant templates or documentation in this Helm chart to reflect this change?

Thank you!