LU-10733 tests: increase conf-sanity/106 OST size

LU-10733 tests: increase conf-sanity/106 OST size

conf-sanity test_106 is trying to create ~64k files, but OST0000
only has about 48k objects in this case, so the file creates are
failing during the test.  This makes the test somewhat unreliable
and hitting errors not related to what was originally intended
(llog wrap handling).

Increase the OSTSIZE for this test to handle the number of objects
needed by the test so it can run more reliably.

Lustre-change: https://review.whamcloud.com/50732
Lustre-commit: 334d780617561c66c91697fb1681ce24b5379387

Test-Parameters: trivial testlist=conf-sanity env=ONLY=106
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: Ie33825801172ea565d9d1d5fb81595d2cad65677
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/50714
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>