LU-18584 tests: fix OSTSIZE for conf-sanity/106

LU-18584 tests: fix OSTSIZE for conf-sanity/106

We try to make sure OST has enough objects for
conf-sanitty/106 but the default bytes to inode
ratio is 16k, not 8k.

Test-Parameters: trivial
Test-Parameters: testlist=conf-sanity env=ONLY=106
Test-Parameters: testlist=conf-sanity env=ONLY=106
Test-Parameters: testlist=conf-sanity env=ONLY=106
Test-Parameters: testlist=conf-sanity env=ONLY=106
Test-Parameters: testlist=conf-sanity env=ONLY=106
Test-Parameters: testlist=conf-sanity env=ONLY=106
Fixes: 334d780617 ("LU-10733 tests: increase conf-sanity/106 OST size")
Signed-off-by: Li Dongyang <dongyangli@ddn.com>
Change-Id: I40fdf909efb5d55741b327708b4a3bb089a53eba
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/57552
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Li Xi <lixi@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>