LU-18098 pcc: increase the async open time slightly for test_40

LU-18098 pcc: increase the async open time slightly for test_40

Occasionally async open time may take a tiny bit longer due to
races in the test case sanity-pcc/test_40.
Increase the async open time slightly and ignore this kind of
error.

Test-Parameters: trivial
Signed-off-by: Qian Yingjin <qian@ddn.com>
Change-Id: I699f14a4c83e6e9700b64522b1ebb360d929e211
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/56225
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Li Xi <lixi@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>