Event change_tracing_layout is also sent when switching viewports

[philippotto]

change_tracing_layout (in onLayoutChange in flex_layout_wrapper.js) should only be sent when the layout changes due to a user action (e.g., a tab is dragged somewhere or resizing is done). However, the event is also sent when I simply click into a viewport.

Reproduction:

• open an annotation (I opened one in read-only mode). not sure whether this also works locally? maybe the events are not sent on localhost in the first place
• click in different viewports
• observe the network tab which should show the analytics events