[chore][receiver/jmx/internal/subprocess] Enable goleak check (#31773)

This originally was failing in CI/CD, but has passed 10+ times in a row,
I think it's safe to merge.

**Link to tracking Issue:**

#30438

receiver/jmxreceiver/internal/subprocess/package_test.go

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