Make bottom panel switch when pinned and removed

[kitbdev]

• related Add a pin toggle to prevent involuntary bottom editor switching #98074

When a bottom panel is opened, pinned, then removed, it doesn't properly change the bottom panel:

This can be seen by moving the Filesystem dock to the bottom panel, pinning it, then moving it out of the bottom panel, or when disabling a custom bottom panel plugin.

Also the Filesystem Editor Docks menu option and the Show in Filesystem action should still switch when the filesystem is at the bottom.

[badsectoracula]

I did a quick test and this works as expected (i was a bit surprised initially because i first tried the behavior without the PR here and when i switched the filesystem dock to the bottom left side again the bottom panel was closed while i expected it to remain open but empty as in the screenshot, so i thought the bug was fixed already but then i tried after also applying the PR and saw the difference in behavior - something to keep in mind by anyone who decides to review this later!).

[Repiteo]

Thanks!