LU-8856 osd: mark specific transactions netfree

LU-8856 osd: mark specific transactions netfree

osd-zfs should mark some transactions netfree. this means those
transactions are expected to release space (rather than consume)
and for this kind of transaction half of reserved space is available.

Lustre-change: https://review.whamcloud.com/31444
Lustre-commit: 106abc184d8b57de560dc1874683ce5487dcf30a

Change-Id: Ia5ca247843b296319376c4ac69efad68b557df9f
Signed-off-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>
Signed-off-by: Minh Diep <minh.diep@intel.com>
Reviewed-on: https://review.whamcloud.com/31751
Tested-by: Jenkins
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>