otelgrpc: Use metricdatatest

[pellared]

I suggest using metricdatatest instead.

	want := metricdata.ScopeMetrics{
		Scope: instrumentation.Scope{
			Name:      "go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc",
			SchemaURL: "https://opentelemetry.io/schemas/1.17.0",
			Version:   otelgrpc.Version(),
		},
		Metrics: []metricdata.Metrics{
			{
				Name:        "rpc.server.duration",
				Description: "Measures the duration of inbound RPC.",
				Unit:        "ms",
				Data: metricdata.Histogram[int64]{
					Temporality: metricdata.CumulativeTemporality,
					DataPoints: []metricdata.HistogramDataPoint[int64]{
						{
							Attributes: attribute.NewSet(
								semconv.RPCMethod(name),
								semconv.RPCService(serviceName),
								otelgrpc.RPCSystemGRPC,
								otelgrpc.GRPCStatusCodeKey.Int64(int64(code)),
							),
						},
					},
				},
			},
		},
	}

	rm := metricdata.ResourceMetrics{}
	err := reader.Collect(context.Background(), &rm)
	assert.NoError(t, err)
	require.Len(t, rm.ScopeMetrics, 1)
	metricdatatest.AssertEqual(t, want, rm.ScopeMetrics[0], metricdatatest.IgnoreTimestamp(), metricdatatest.IgnoreValue())

To make this working you would also need to change the TestUnaryServerInterceptor to update to setup providers, recorders etc for each test case. I also noticed that the providers are not being shutdown.

I think it is better to address it in a separate PR as I think this refactoring could be done for most of the gRPC tests.

Originally posted by @pellared in #4481 (comment)