upgradesstables/scrub support for 2.x sstables

This support is important for 2.0/3.0 cluster or 3.0/4.0 cluster that can/might contain 2.x sstables.

4.0 supports versions down to ma, and 3.0 supports versions down to jb (3.0 and 2.0.1 correspondingly). So by the time you're on 4.0, you should have no 2.0 sstables either way, and this needs to be fixed for 3.11

NOTE: I just marked the ticket with both 3.11 and 4.0 rc versions even if the bug is presented only in 3.11 but to make it appear as a blocker on the 4.0 board!!