[Status Bar] Don't mess with status bar visibility in extensions
"Extensions" is additions to the status bar like free space bar and zoom slider which should hide while loading.
The status bar itself should only show/hide based on the global setting.
Backport to stable I guess
- Status bar no lonager intermittently hides while loading a directory
- Changing status bar visibility setting in Dolphin works
- Dolphin starts with correct status bar visibility