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.

scripts/develop/main_test.go

@@ -101,13 +101,11 @@ func TestLogWriter(t *testing.T) {
 
 		var wg sync.WaitGroup
 		for range 10 {
-			wg.Add(1)
-			go func() {
-				defer wg.Done()
+			wg.Go(func() {
 				for range 50 {
 					_, _ = w.Write([]byte("x\n"))
 				}
-			}()
+			})
 		}
 		wg.Wait()