LU-18072 ptlrpc: do not search for duplicate cancel requests

LU-18072 ptlrpc: do not search for duplicate cancel requests

Cancel requests don't have any max inflight limitations, so
really could arrive in huge numbers and if they are also have a resent
flag, that leads to a lot of very expensive duplicates search that is
totally unneeded at the same time, so let's skip the check for cancels.

Change-Id: Id4be03a3c9406867adcdcfd31ed91ecc7b12f700
Signed-off-by: Oleg Drokin <green@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/56843
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andriy Skulysh <andriy.skulysh@hpe.com>
Reviewed-by: Mikhail Pershin <mpershin@whamcloud.com>
Reviewed-by: Olaf Faaland <faaland1@llnl.gov>