fix: align registerPluginSettings name with deploy directory 'polaris'

The shared volume deploy script places the plugin at /headlamp/plugins/polaris/,
so Headlamp matches settings by directory name 'polaris', not the package.json
name 'headlamp-polaris'. This reverts commit b9d718b which incorrectly changed
the registration name back to 'headlamp-polaris'.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

src/index.tsx

@@ -99,7 +99,7 @@ registerRoute({
 });
 
 // Register plugin settings
-registerPluginSettings('headlamp-polaris', PolarisSettings, true);
+registerPluginSettings('polaris', PolarisSettings, true);
 
 // Register details view section for supported controller types
 registerDetailsViewSection(({ resource }) => {