Fix T81969 VSE: Wrong UI colorspace after scene strip update

This regression was caused by rB57de5686048f which disabled srgb
transform after the python callback.

The right thing to do is to only rebind the framebuffer once to
reset the no-srgb override.

source/blender/editors/screen/area.c

@@ -550,10 +550,11 @@ void ED_region_do_draw(bContext *C, ARegion *region)
    * for drawing of borders/gestures etc */
   ED_region_pixelspace(region);
 
+  /* Remove sRGB override by rebinding the framebuffer. */
   GPUFrameBuffer *fb = GPU_framebuffer_active_get();
   GPU_framebuffer_bind(fb);
+
   ED_region_draw_cb_draw(C, region, REGION_DRAW_POST_PIXEL);
-  GPU_framebuffer_bind_no_srgb(fb);
 
   region_draw_azones(area, region);