[chore][receiver/snowflake] Enable goleak check (open-telemetry#32182)

**Description:**
This enables the `goleak` check for the Snowflake receiver to help
ensure no goroutines are being leaked. This is a test only change, a
couple shutdown/close calls were missing.

**Link to tracking Issue:** open-telemetry#30438

**Testing:** 
All existing tests are passing, as well as added `goleak` check.

receiver/snowflakereceiver/client_test.go

@@ -18,7 +18,7 @@ import (
 )
 
 func TestDefaultClientCreation(t *testing.T) {
-	_, err := newDefaultClient(componenttest.NewNopTelemetrySettings(), Config{
+	c, err := newDefaultClient(componenttest.NewNopTelemetrySettings(), Config{
 		Username:  "testuser",
 		Password:  "testPassword",
 		Account:   "testAccount",
@@ -27,7 +27,8 @@ func TestDefaultClientCreation(t *testing.T) {
 		Database:  "testDatabase",
 		Role:      "testRole",
 	})
-	assert.Equal(t, nil, err)
+	assert.NoError(t, err)
+	assert.NoError(t, c.client.Close())
 }
 
 // test query wrapper

receiver/snowflakereceiver/package_test.go

@@ -0,0 +1,15 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package snowflakereceiver
+
+import (
+	"testing"
+
+	"go.uber.org/goleak"
+)
+
+// Regarding the godbus/dbus ignore: see https://github.com/99designs/keyring/issues/103
+func TestMain(m *testing.M) {
+	goleak.VerifyTestMain(m, goleak.IgnoreAnyFunction("github.com/godbus/dbus.(*Conn).inWorker"))
+}

receiver/snowflakereceiver/scraper_test.go

@@ -72,6 +72,7 @@ func TestStart(t *testing.T) {
 	scraper := newSnowflakeMetricsScraper(receivertest.NewNopCreateSettings(), cfg)
 	err := scraper.start(context.Background(), componenttest.NewNopHost())
 	require.NoError(t, err, "Problem starting scraper")
+	require.NoError(t, scraper.shutdown(context.Background()))
 }
 
 // wrapper type for convenience