feat(server): delete unnecessary encoded videos

[mertalev]

Description

The current transcoding behavior only allows for the creation or replacement of encoded videos, but not their deletion. This means if an admin decides to change their transcode policy after videos have been transcoded, previous transcodes will continue to exist even if the new policy doesn't require them. This PR adds a check to the transcoding job handler to delete encoded videos in cases where there is an existing transcode despite the current policy.

Fixes #5873

How Has This Been Tested?

1. Inspect the encoded-video directory with find encoded-video -name *.mp4, confirming there are videos there
2. Set the transcode policy to disabled
3. Run transcoding jobs for all videos
4. Confirm that the microservices container has logs about deleting transcodes
5. Confirm that find encoded-video -name *.mp4 does not return any videos

[alextran1502]

Besides disabling policy, other policies would overwrite the transcoded videos, correct?

[mertalev]

All will always overwrite existing transcodes, disabled will always delete them, and for the other policies it depends on whether the video meets the conditions to transcode. If it does, then the existing transcode gets overwritten. If not, then it gets deleted.