cbbackupmgr cloud restore should handle restoring from a read only bucket

If may seem like a restore is a read only operation, however, there are a few things that happen at the archive level where we modify/create some files.

1) We create a lockfile
2) We (possibly) remove rotated logfiles
3) We upload logs on completion

cbbackupmgr should be able to handle these scenarios gracefully allowing users to restore from read only buckets.