LU-17046 tests: fix write success in 1g

LU-17046 tests: fix write success in 1g

Increase latest write count in 3 times. This may
happen that the previous write didn't write requested
amount of data. For example, if it had to write 20MB, but
wrote only 17, the final write need to write at least 3MB
to hit EDQUOT. If there are only 2 OSTs it writes only
19MB(17+2) and can't hit EDQUOT.

Test-Parameters: trivial testlist=sanity-quota
Test-Parameters: trivial testlist=sanity-quota
Test-Parameters: trivial testlist=sanity-quota
Signed-off-by: Sergey Cheremencev <scherementsev@ddn.com>
Change-Id: Ice5152fa4ba8504eda2ea5513201e340c5ff6220
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/53038
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Timothy Day <timday@amazon.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>