[Profiler] [UI] Selected label contains data after cleanup

To reproduce:

1. Create new project and profile some data from Playmode.
2. In CPU detailed view select one of processes (E.g. WaitForRenderJobs).
Note: Notie that label "Selected: WaitForRenderJobs" is selected in graph view.
3. Press Clear.

Expected result: All frames and data are cleaned from Profilew window.
Actual result: Label "Selected: WaitForRenderJobs" is still displayed.

Reasoning for closing:
While this might seem like we're missing something in our cleanup, this is intentional. The selected sample gets tracked even if the selection is no longer there or even if the data is cleared. The use cases for this are, for example, to track a sample across runs of the player, while having "Clear on Play" on to avoid potential confusions with frames from the older runs. Similarly, one might want to clear for the same purpose during a profiling session but still want the sample tracked and its portion of the time highlighted in the charts.

We don't see a use case that would benefit from clearing it, but it could hurt the use cases outlined above. If there is a use case, for which it is important to clear it, we're happy to consider it.