Validate known "dangerous" buckets configurations when creating a new "backup" task

Version: 3.4

## Description
There are known (but apparently not documented) configurations of buckets that should not be used in order for SM backup and restore to work properly.

For example, a "lifecycle" S3 configuration.

Scylla Manager should not not only document all such limitations but also proactively verify them every time a new `backup` task is created.