[chore][receiver/sapmreceiver] Enable goleak check (open-telemetry#31666

)

**Description:** <Describe what has changed.>
<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
Enable goleak checks on the sapm receiver to help ensure no goroutines
are being leaked. This is a test only change, some response bodies
weren't being closed in tests.

**Link to tracking Issue:** <Issue number if applicable>

open-telemetry#30438

receiver/sapmreceiver/go.mod

@@ -21,6 +21,7 @@ require (
 	go.opentelemetry.io/collector/semconv v0.96.1-0.20240306115632-b2693620eff6
 	go.opentelemetry.io/otel/metric v1.24.0
 	go.opentelemetry.io/otel/trace v1.24.0
+	go.uber.org/goleak v1.3.0
 )
 
 require (

receiver/sapmreceiver/package_test.go

@@ -0,0 +1,14 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package sapmreceiver
+
+import (
+	"testing"
+
+	"go.uber.org/goleak"
+)
+
+func TestMain(m *testing.M) {
+	goleak.VerifyTestMain(m)
+}

receiver/sapmreceiver/trace_receiver_test.go

@@ -340,6 +340,7 @@ func TestReception(t *testing.T) {
 			resp, err := sendSapm(tt.args.config.Endpoint, tt.args.sapm, tt.args.compression, tt.args.useTLS, "")
 			require.NoError(t, err)
 			assert.Equal(t, 200, resp.StatusCode)
+			assert.NoError(t, resp.Body.Close())
 			t.Log("SAPM Request Received")
 
 			// retrieve received traces
@@ -405,6 +406,7 @@ func TestAccessTokenPassthrough(t *testing.T) {
 			resp, err := sendSapm(config.Endpoint, sapm, "gzip", false, tt.token)
 			require.NoErrorf(t, err, "should not have failed when sending sapm %v", err)
 			assert.Equal(t, 200, resp.StatusCode)
+			assert.NoError(t, resp.Body.Close())
 
 			got := sink.AllTraces()
 			assert.Equal(t, 1, len(got))