AWS adot collector (using otelp and emf exporter) not sending http.route

[Ryang20718]

Description

When using the otel adot collector with otelp, emf exporter enabled, the field http.route doesn't get ingested to cloudwatch

Steps to Reproduce

spin up an aws otel collector with aws emf being an exporter. instrument the sample app in something like

import(
	"go.opentelemetry.io/contrib/instrumentation/github.com/gin-gonic/gin/otelgin"
   "go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
)


       // tracing setup here for otel
       
       // tracing middleware
       
	router := gin.New()
   router.Use(otelgin.Middleware(config.OtelServiceName))

	mux := http.NewServeMux()
	mux.Handle("/api/", router)

	otelHTTPHandler := otelhttp.NewHandler(mux, "")

       httpServer := &http.Server{
           ReadHeaderTimeout: 1 * time.Minute,
           Addr:              ":8080",
           Handler:           otelHTTPHandler,
       }
       return httpServer.ListenAndServe()

Expected Result

we should see http.route appear as a field in cloudwatch metrics

Actual Result

we don't see http.route appear as a field in cloudwatch metrics

Collector version

0.0.74

Environment information

Environment

OS: (e.g., "Ubuntu 20.04")
GO = 1.20.4

OpenTelemetry Collector configuration

extensions:
  health_check:
  pprof:
    endpoint: 0.0.0.0:1777

receivers:
  otlp:
    protocols:
      grpc:
        endpoint: 0.0.0.0:4317

processors:
  batch:

exporters:
  logging:
    loglevel: debug
  awsemf:
    region: 'us-west-2'

service:
  pipelines:
    metrics:
      receivers: [otlp]
      exporters: [awsemf]

  extensions: [pprof]
  telemetry:
    logs:
      level: debug

CMD:

    docker run --rm -p 4317:4317 -p 55680:55680 -p 8889:8888 \
      -e AWS_REGION=us-west-2 \
      -e AWS_PROFILE=default \
      -v ~/.aws:/root/.aws \
      -v "${PWD}/examples/docker/config-test.yaml":/otel-local-config.yaml \
      --name awscollector public.ecr.aws/aws-observability/aws-otel-collector:latest \
      --config otel-local-config.yaml;

Log output

{
    "OTelLib": "go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp",
    "Version": "1",
    "_aws": {
        "CloudWatchMetrics": [
            {
                "Namespace": "testing",
                "Dimensions": [
                    [
                        "OTelLib",
                        "http.scheme",
                        "http.status_code",
                        "net.sock.peer.port",
                        "net.host.name",
                        "net.host.port",
                        "net.sock.peer.addr",
                        "http.flavor",
                        "http.method",
                        "http.user_agent"
                    ],
                    [
                        "OTelLib"
                    ],
                    [
                        "OTelLib",
                        "http.status_code"
                    ],
                    [
                        "OTelLib",
                        "net.sock.peer.port"
                    ],
                    [
                        "OTelLib",
                        "http.scheme"
                    ],
                    [
                        "OTelLib",
                        "http.method"
                    ],
                    [
                        "OTelLib",
                        "http.user_agent"
                    ],
                    [
                        "OTelLib",
                        "net.host.name"
                    ],
                    [
                        "OTelLib",
                        "net.host.port"
                    ],
                    [
                        "OTelLib",
                        "net.sock.peer.addr"
                    ],
                    [
                        "OTelLib",
                        "http.flavor"
                    ]
                ],
                "Metrics": [
                    {
                        "Name": "http.server.duration"
                    }
                ]
            }
        ],
        "Timestamp": 1686603548366
    },
    "http.flavor": "1.1",
    "http.method": "GET",
    "http.scheme": "http",
    "http.server.duration": {
        "Max": 1.26,
        "Min": 0.14,
        "Count": 3,
        "Sum": 2.43
    },
    "http.status_code": "304",
    "http.user_agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/114.0.0.0 Safari/537.36",
    "net.host.name": "localhost",
    "net.host.port": "8080",
    "net.sock.peer.addr": "172.19.0.1",
    "net.sock.peer.port": "55952"
}

### Additional context

It seems the EMF exporter is filtering out http.route even with default configurations? We're able to get http.route when using other exporters such as aws xray.