Fix: VSE: Remove Playhead Snapping menu from Preview

The other snapping menu in the preview is specific to that view type,
so it doesn't really make sense to have a timeline-specific snap
mode listed here.

Pull Request: https://projects.blender.org/blender/blender/pulls/140171

scripts/startup/bl_ui/space_sequencer.py

@@ -189,7 +189,8 @@ class SEQUENCER_HT_header(Header):
         row.prop(tool_settings, "use_snap_sequencer", text="")
         sub = row.row(align=True)
         sub.popover(panel="SEQUENCER_PT_snapping")
-        layout.popover(panel="SEQUENCER_PT_playhead_snapping")
+        if st.view_type in {'SEQUENCER', 'SEQUENCER_PREVIEW'}:
+            layout.popover(panel="SEQUENCER_PT_playhead_snapping")
         layout.separator_spacer()
 
         if st.view_type in {'PREVIEW', 'SEQUENCER_PREVIEW'}: