Removed Profile::getCallgraphNodes method in use

[glensc]

35dff59 removed Profile::getCallgraphNodes method, but it's referred from callgraphDataDot route:

• xhgui/src/Controller/RunController.php

  Line 365 in 4c2bca3

  $callgraph = $profile->getCallgraphNodes($metric, $threshold);

@markstory can you dig up what is this? and what should be done with this now?

[glensc]

The commit comes from PR: #126