Switching between threads should not change the selected panel (don't hide Call Tree panel if there exists a thread with samples)

Switching threads can get you "stuck" on the marker panel when you didn't mean to switch panels.

Steps to reproduce:

1. Load this profile: https://share.firefox.dev/3IBw8Gb
1. Click the "BHMgr Processor" thread.
1. Click the main thread again.

Expected results:
You should be back in the call tree.

Actual results:
You are now on the marker chart.

Even at step 2, the message `The marker chart is empty for “BHMgr Processor”` is not helpful - I was interested in samples, not in markers.

- - -
Hiding the call tree is useful for profiles which don't have any samples in them at all. But I think as soon as there's at least one thread with samples, we should keep the panels consistent between threads.

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-643)