Remove unused drawBorder() method in CTabFolderRenderer #10391

Job	Run time
Event File	3s
Detect changed paths	4s
Build (macOS) (21, x86_64) / build	19m 24s
Build (macOS) (21, aarch64) / build	6m 48s
Build (Linux) (21, gtk4, wayland) / build	29m 6s
Build (Linux) (21, gtk4, x11) / build	16m 53s
Build (Windows) (21) / build	11m 37s
Build (Linux) (21, gtk3, x11) / build	9m 9s
	1h 33m 4s

Provide feedback