The issue with the existing code is that we use the
`page.waitForSelector` function to detect if the element
is visible and interactable.
`page.waitForSelector` only ensures that the element is
visible and doesn't guarantees that the element is
interactable. Most of the time it is enough but sometimes
it is too fast and our test fails.
To fix this we change our approach to check the button
text on the stream settings page (`/#streams/stream_id`).
Either it could be `Subscribe` or `Unsubscribe`.
Riken Shah
Steve Howell