LU-17428 ldlm: reduce default lru_max_age

LU-17428 ldlm: reduce default lru_max_age

Decrease the default value of lru_max_age from 3900s to 600s.
Otherwise, clients can accumulate too many old locks.

Fixes: fe60e0135e ("LU-6529 ldlm: reclaim granted locks defensively")
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I93e288491c868b79162620336830290a85529f0d
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/53682
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Timothy Day <timday@amazon.com>
Reviewed-by: Patrick Farrell <patrick.farrell@oracle.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>