fix: Use standard env variables for opentelemtry (#2194)

Opentelemetry defines standard variables which are supported by multiple observability platforms.

[1] https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/sdk-environment-variables.md
[2] https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/exporter.md

By defining support for standard env vars, Fission open telemetry support can be leveraged with different
platforms such as NewRelic, SigNoz, DataDog etc.

Signed-off-by: Sanket Sudake <sanketsudake@gmail.com>

pkg/fetcher/config/config.go

@@ -18,6 +18,7 @@ import (
 	fv1 "github.com/fission/fission/pkg/apis/core/v1"
 	"github.com/fission/fission/pkg/fetcher"
 	"github.com/fission/fission/pkg/utils"
+	"github.com/fission/fission/pkg/utils/otel"
 )
 
 type Config struct {
@@ -283,16 +284,7 @@ func (cfg *Config) addFetcherToPodSpecWithCommand(podSpec *apiv1.PodSpec, mainCo
 				},
 			},
 		},
-		Env: []apiv1.EnvVar{
-			{
-				Name:  "OPENTRACING_ENABLED",
-				Value: os.Getenv("OPENTRACING_ENABLED"),
-			},
-			{
-				Name:  "OTEL_COLLECTOR_ENDPOINT",
-				Value: os.Getenv("OTEL_COLLECTOR_ENDPOINT"),
-			},
-		},
+		Env: otel.OtelEnvForContainer(),
 	}
 
 	// Pod is removed from endpoints list for service when it's