test: Fix race condition in testNodeNavigation (#8365)
test: Fix race condition in testNodeNavigation (#8365)

The Troubleshoot button quickly appears and disappears while the
"Connecting to machine..." spinner is shown. Wait for that to go away
first before waiting for the Troubleshoot button. Fixes this race:

```
-> wait: ph_is_visible("#machine-troubleshoot")
<- {u'type': u'undefined'}
-> ph_click("#machine-troubleshoot",false)
<- {u'type': u'string', u'value': u'#machine-troubleshoot is not visible'}
Traceback (most recent call last):
  File "/home/martin/upstream/cockpit/test/verify/kubelib.py", line 793, in testNodeNavigation
    b.click('#machine-troubleshoot')
  File "/home/martin/upstream/cockpit/test/common/testlib.py", line 202, in click
    self.call_js_func('ph_click', selector, force)
  File "/home/martin/upstream/cockpit/test/common/testlib.py", line 187, in call_js_func
    return self.eval_js("%s(%s)" % (func, ','.join(map(jsquote, args))))
  File "/home/martin/upstream/cockpit/test/common/testlib.py", line 173, in eval_js
    self.raise_cdp_exception("eval_js", code, result["exceptionDetails"])
  File "/home/martin/upstream/cockpit/test/common/testlib.py", line 167, in raise_cdp_exception
    raise Error("%s(%s): %s" % (func, arg, msg))
Error: eval_js(ph_click("#machine-troubleshoot",false)): #machine-troubleshoot is not visible
```

Fixes #8364
Closes #8365
mareklibra/cockpit,mvollmer/cockpit,petervo/cockpit,petervo/cockpit,garrett/cockpit,petervo/cockpit,deryni/cockpit,cockpituous/cockpit,deryni/cockpit,SotolitoLabs/cockpit,deryni/cockpit,mareklibra/cockpit,moraleslazaro/cockpit,mvollmer/cockpit,Scribery/cockpit,petervo/cockpit,andreasn/cockpit,martinpitt/cockpit,andreasn/cockpit,cockpit-project/cockpit,garrett/cockpit,mvollmer/cockpit,moraleslazaro/cockpit,andreasn/cockpit,stefwalter/cockpit,andreasn/cockpit,Scribery/cockpit,Scribery/cockpit,SotolitoLabs/cockpit,Scribery/cockpit,garrett/cockpit,deryni/cockpit,cockpituous/cockpit,andreasn/cockpit,SotolitoLabs/cockpit,stefwalter/cockpit,stefwalter/cockpit,garrett/cockpit,Scribery/cockpit,cockpit-project/cockpit,petervo/cockpit,mareklibra/cockpit,Scribery/cockpit,stefwalter/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,stefwalter/cockpit,mareklibra/cockpit,martinpitt/cockpit,cockpit-project/cockpit,mareklibra/cockpit,SotolitoLabs/cockpit,SotolitoLabs/cockpit,stefwalter/cockpit,martinpitt/cockpit,deryni/cockpit,cockpit-project/cockpit,stefwalter/cockpit,moraleslazaro/cockpit,cockpit-project/cockpit,SotolitoLabs/cockpit,mareklibra/cockpit,moraleslazaro/cockpit,deryni/cockpit,Scribery/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,martinpitt/cockpit,deryni/cockpit,mareklibra/cockpit,petervo/cockpit,mvollmer/cockpit,mvollmer/cockpit,andreasn/cockpit,cockpituous/cockpit,SotolitoLabs/cockpit,andreasn/cockpit,martinpitt/cockpit,cockpituous/cockpit,garrett/cockpit,petervo/cockpit