[chore][internal/aws/k8s/k8sclient] Enable goleak check (open-telemet…

…ry#30761)

**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.-->
This adds the `goleak` check for the `internal/aws/k8s/k8sclient`
package. The only update needed was to add a missing `shutdown` call to
a client in a test. This was a test only change.

**Link to tracking Issue:** <Issue number if applicable>
open-telemetry#30438

**Testing:** <Describe what testing was performed and which tests were
added.>
All tests are passing, as well as added goleak check.

---------

Co-authored-by: Pablo Baeyens <pbaeyens31+github@gmail.com>

internal/aws/k8s/k8sclient/endpoint_test.go

@@ -416,5 +416,6 @@ func TestNewEndpointClient(t *testing.T) {
 	fakeClientSet := fake.NewSimpleClientset(endpointsArray...)
 	client := newEpClient(fakeClientSet, zap.NewNop(), setOption)
 	assert.NotNil(t, client)
+	client.shutdown()
 	removeTempKubeConfig()
 }

internal/aws/k8s/k8sclient/package_test.go

@@ -0,0 +1,14 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package k8sclient
+
+import (
+	"testing"
+
+	"go.uber.org/goleak"
+)
+
+func TestMain(m *testing.M) {
+	goleak.VerifyTestMain(m)
+}