[chore][cmd/configschema/docsgen/docsgen] Enable goleak (open-telemetry#30494)

**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.-->
Enables `goleak` on the `docsgen` package to catch potential leaking
goroutines.

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

**Testing:** <Describe what testing was performed and which tests were
added.>
Test is passing other than referenced failure.

---------

Co-authored-by: Pablo Baeyens <[email protected]>

Author: 2 people

cmd/configschema/docsgen/docsgen/package_test.go

@@ -0,0 +1,31 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package docsgen
+
+import (
+	"testing"
+
+	"go.uber.org/goleak"
+)
+
+// The Ignore function calls prevent catching leaks generated by indirect dependencies.
+// All of these are leaks that we can't fix from within the collector code base.
+// Regarding the OpenCensus ignore: see https://github.com/census-instrumentation/opencensus-go/issues/1191
+// Regarding the DataDog ignore: see https://github.com/DataDog/datadog-agent/issues/22030
+// Regarding the database/sql ignore: see https://github.com/SAP/go-hdb/issues/130
+// Regarding the SAP/go-hdb ignore: see https://github.com/SAP/go-hdb/issues/131
+// Regarding the cihub/seelog ignore: see https://github.com/cihub/seelog/issues/182
+// Regarding the godbus/dbus ignore: see https://github.com/99designs/keyring/issues/135
+func TestMain(m *testing.M) {
+	goleak.VerifyTestMain(m,
+		goleak.IgnoreTopFunction("go.opencensus.io/stats/view.(*worker).start"),
+		goleak.IgnoreTopFunction("github.com/DataDog/datadog-agent/pkg/trace/metrics/timing.(*Set).Autoreport.func1"),
+		// Unfortunately this ignore can't be anymore specific, even though it's caused by the SAP/go-hdb/driver
+		// package. There's no reference to this package in the goleak output. This has the potential of
+		// hiding future leaks, so we should remove as soon as the referenced issue is resolved.
+		goleak.IgnoreTopFunction("database/sql.(*DB).connectionOpener"),
+		goleak.IgnoreTopFunction("github.com/SAP/go-hdb/driver.(*metrics).collect"),
+		goleak.IgnoreAnyFunction("github.com/cihub/seelog.(*asyncLoopLogger).processQueue"),
+		goleak.IgnoreAnyFunction("github.com/godbus/dbus.(*Conn).inWorker"))
+}