Reintroduce service finish telemetry

Problem

Service finish telemetry was disabled after it generated a huge spike in events from 60k to 2.5m per day. The spike was caused by crash looping services sending telemetry events every time they exited, even when the exit code didn't change.

Impact

Without this telemetry, we can't see when services actually fail and debugging becomes harder.

Proposal

Reintroduce service finish telemetry but only emit events when the service exit code changes.

Impacted categories

The following categories relate to this issue:

• gdk-reliability - e.g. When a GDK action fails to complete.
• gdk-usability - e.g. Improvements or suggestions around how the GDK functions.
• gdk-performance - e.g. When a GDK action is slow or times out.