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/utils/tracing/tracing.go

@@ -11,7 +11,11 @@ import (
 )
 
 func TracingEnabled(logger *zap.Logger) bool {
-	openTracingEnabled, err := strconv.ParseBool(os.Getenv("OPENTRACING_ENABLED"))
+	tracingEnabled := os.Getenv("TRACING_ENABLED")
+	if len(tracingEnabled) == 0 {
+		return false
+	}
+	openTracingEnabled, err := strconv.ParseBool(tracingEnabled)
 	if err != nil {
 		if logger != nil {
 			logger.Error("Error parsing OpenTracing enabled flag", zap.Error(err))