admin: default -dataDir to "." so maintenance task state persists
Previously -dataDir defaulted to empty, so the admin ran maintenance in
memory only: task state was never saved and maintenance tasks (notably EC
balance/rebuild) were re-issued every scan cycle without converging,
churning EC shards (moves landed shards without their .ecx index, leaving
EC volumes unloadable/missing shards).
Default -dataDir to "." (the process working directory, which under the
standard systemd unit is the admin's data dir) so state persists out of
the box.
Chris Lu
89cbb1c558