fix(coderd): remove CREATE INDEX CONCURRENTLY from migrations (#8353)

coderd/database/migrations/000074_workspace_resources_job_id_idx.up.sql

@@ -1 +1 @@
-CREATE INDEX CONCURRENTLY workspace_resources_job_id_idx ON workspace_resources USING btree (job_id);
+CREATE INDEX workspace_resources_job_id_idx ON workspace_resources USING btree (job_id);

coderd/database/migrations/migrate_test.go

@@ -20,6 +20,7 @@ import (
 	"github.com/stretchr/testify/require"
 	"go.uber.org/goleak"
 	"golang.org/x/exp/slices"
+	"golang.org/x/sync/errgroup"
 
 	"github.com/coder/coder/coderd/database/migrations"
 	"github.com/coder/coder/coderd/database/postgres"
@@ -47,6 +48,22 @@ func TestMigrate(t *testing.T) {
 		require.NoError(t, err)
 	})
 
+	t.Run("Parallel", func(t *testing.T) {
+		t.Parallel()
+
+		db := testSQLDB(t)
+		eg := errgroup.Group{}
+
+		eg.Go(func() error {
+			return migrations.Up(db)
+		})
+		eg.Go(func() error {
+			return migrations.Up(db)
+		})
+
+		require.NoError(t, eg.Wait())
+	})
+
 	t.Run("Twice", func(t *testing.T) {
 		t.Parallel()
 
@@ -86,6 +103,13 @@ func testSQLDB(t testing.TB) *sql.DB {
 	require.NoError(t, err)
 	t.Cleanup(func() { _ = db.Close() })
 
+	// postgres.Open automatically runs migrations, but we want to actually test
+	// migration behavior in this package.
+	_, err = db.Exec(`DROP SCHEMA public CASCADE`)
+	require.NoError(t, err)
+	_, err = db.Exec(`CREATE SCHEMA public`)
+	require.NoError(t, err)
+
 	return db
 }