Replace /rclone/sync/movedir with /storage_service/backup to use scylla streaming

[karol-kokoszka]

Current effort on core side is expected to bring the feature where the data is send to AWS S3 (to be validated what about GCS and Azure) directly by Scylla server.
Scylla Manager is currently using RClone under the hood to send the data to S3.

This issue expects Scylla Manager to start using /storage_service/backup endpoint of Scylla server instead of the RClone one. https://docs.google.com/document/d/1d-nJnn5n2gqzRXvP5xpOis0fWxIzYkf-u9X1xrIAG_c/edit?tab=t.0#bookmark=id.9g3y3uw716bc

PR cannot be merged to master, we just want to keep it on feature branch until there is a green light that all corner cases are covered and we finally can get rid of RClone.