Bump waitForStopped timeout further.

I am hitting the 15-second deadline for llama2-70b @ fp16. It's a beast of a
model with ~130GiB of RAM.

PiperOrigin-RevId: 620382594

runsc/sandbox/sandbox.go

@@ -1462,7 +1462,7 @@ func (s *Sandbox) waitForStopped() error {
 		return nil
 	}
 
-	ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
+	ctx, cancel := context.WithTimeout(context.Background(), 45*time.Second)
 	defer cancel()
 	b := backoff.WithContext(backoff.NewConstantBackOff(100*time.Millisecond), ctx)
 	op := func() error {