Improve output for "Waiting for tidb instances ready"

[dveeden]

Feature Request

In some cases tiup playground prints this message many times while it waits for tidb to be ready: "Waiting for tidb instances ready"

Would be nice to have it print "Waiting for tidb instances ready" an then print a "." every second and move the cursor back again every 3s. Or the spinner animation that tiup uses elsewhere. Then it doesn't eat as much screen space.

I also think the message itself should be changed to "Waiting for tidb instances to be ready"

[9547]

/assign