LU-11170 test: increase time limit in sanity test_415

LU-11170 test: increase time limit in sanity test_415

In sanity test_415() double the time limit on renaming 500
files. Really we should not be doing arbitrary performance tests using
VMs on oversubscribed test nodes but whatever.

Test-Parameters: trivial testlist=sanity env=ONLY=415,ONLY_REPEAT=10
Signed-off-by: John L. Hammond <jhammond@whamcloud.com>
Change-Id: Ie2677df00f13ffc85d21ceba5ba7115fff6f0980
Reviewed-on: https://review.whamcloud.com/47341
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Nathaniel Clark <nclark@whamcloud.com>
Reviewed-by: Lai Siyao <lai.siyao@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>