refactor: use sync.WaitGroup.Go in tests (#26671)

Migrate `wg.Add(1); go func() { defer wg.Done(); ... }()` to
`wg.Go(func() { ... })` in tests.

Where the prior pattern passed the loop variable explicitly via a
closure parameter (`go func(id int) { ... }(i)`), drop the parameter and
reference the loop variable directly. Per-iteration loop variables since
Go 1.22 make this safe.

enterprise/coderd/prebuilds/reconcile_test.go

@@ -1974,9 +1974,7 @@ func TestReconciliationLock(t *testing.T) {
 	wg := sync.WaitGroup{}
 	mutex := sync.Mutex{}
 	for i := 0; i < 5; i++ {
-		wg.Add(1)
-		go func() {
-			defer wg.Done()
+		wg.Go(func() {
 			cache := files.New(prometheus.NewRegistry(), &coderdtest.FakeAuthorizer{})
 			reconciler := prebuilds.NewStoreReconciler(
 				db,
@@ -2002,7 +2000,7 @@ func TestReconciliationLock(t *testing.T) {
 				defer mutex.Unlock()
 				return nil
 			})
-		}()
+		})
 	}
 	wg.Wait()
 }

enterprise/coderd/workspacequota_test.go

@@ -152,13 +152,11 @@ func TestWorkspaceQuota(t *testing.T) {
 		// Spin up three workspaces fine
 		var wg sync.WaitGroup
 		for i := 0; i < 4; i++ {
-			wg.Add(1)
-			go func() {
-				defer wg.Done()
+			wg.Go(func() {
 				workspace := coderdtest.CreateWorkspace(t, client, template.ID)
 				build := coderdtest.AwaitWorkspaceBuildJobCompleted(t, client, workspace.LatestBuild.ID)
 				assert.Equal(t, codersdk.WorkspaceStatusRunning, build.Status)
-			}()
+			})
 		}
 		wg.Wait()
 		verifyQuota(ctx, t, client, user.OrganizationID.String(), 4, 4)