Enabled configuration of OTEL service name via environment variable

When running multiple functional instances of the SATP Gateway (one gateway for network 1, one gateway for network 2) you need for each instance a unique OTEL service name to keep logging, traces and metrics separated.

As per the documentation here: 

https://opentelemetry.io/docs/specs/otel/configuration/sdk-environment-variables/#general-sdk-configuration 

...I have used the standard environment variable OTEL_SERVICE_NAME to allow for this.

Signed-off-by: Robin Huiser <[email protected]>

Author: rhuiser

packages/cactus-plugin-satp-hermes/src/main/typescript/services/monitoring/monitor.ts

@@ -147,7 +147,7 @@ export class MonitorService {
     }
 
     const resource = new Resource({
-      "service.name": "Satp-Hermes-Gateway",
+      "service.name": process.env.OTEL_SERVICE_NAME || "Satp-Hermes-Gateway",
     });
 
     if (!this.sdk) {