fix mmdet3.x InstanceSeg_Tutorial demo api

[sanbuphy]

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[ZwwWayne]

Hi @sanbuphy ,
Thanks for your kind PR.
For now, the tutorial seems to be a little big. Is there any way to reduce its size?

[sanbuphy]

Hi @sanbuphy , Thanks for your kind PR. For now, the tutorial seems to be a little big. Is there any way to reduce its size?

Hi, I tried to reduce the size to 12.4MB , it less then MMDet_Tutorial.ipynb .

[RangiLyu]

Set draw_gt = False, here to avoid visualizing the original image.

[sanbuphy]

Set draw_gt = False, here to avoid visualizing the original image.

OK, I have fixed it.