While retranscoding the old thumbnail should get removed

[kjnanda]

During the retranscode, there could the the media files which were already transcoded. That means there will be a thumbnail as well for each file.

Now, for the better user experience, we should remove the previously generated thumbnail.

[kjnanda]

NOTE: I have tested this with only VIP plugin. Please cross-check if this happens with non VIP code as well.

CC @dhaval-parekh

[dhaval-parekh]

@kjnanda I have added this feature. Please have a look at the below sites.

• https://dharmin.dev3.rt.gw/
• https://thumbnail-demo.dev3.rt.gw/