LU-16367 utils: clean up ldiskfs feature handling

LU-16367 utils: clean up ldiskfs feature handling

Update the default ldiskfs features used by mkfs.lustre:
- enable large_dir on OSTs as well as MDTs
- remove obsolete handling of "ext3" filesystems
- clean up handling of other features that have become a bit messy

Test-Parameters: trivial testlist=conf-sanity
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: Id717c3ba939ccf9b2de34e868d4415e88429ef39
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/49316
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Li Dongyang <dongyangli@ddn.com>
Reviewed-by: Artem Blagodarenko <ablagodarenko@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>