Output '*kilobytes' metrics to KB

[RDruon]

Fixes EX-7902

Demo

get_param:

[root@vm-001 ~]# lctl  get_param osd-*.*.kbytesavail
osd-ldiskfs.MGS.kbytesavail=1874028
osd-ldiskfs.testfs-MDT0000.kbytesavail=3388879012
[root@vm-001 ~]# lctl get_param osd-*.*.kbytesfree
osd-ldiskfs.MGS.kbytesfree=1978884
osd-ldiskfs.testfs-MDT0000.kbytesfree=3446861004
[root@vm-001 ~]# lctl get_param osd-*.*.kbytestotal
osd-ldiskfs.MGS.kbytestotal=1980036
osd-ldiskfs.testfs-MDT0000.kbytestotal=3446866632

exporter:

# HELP lustre_available_kilobytes Number of kilobytes readily available in the pool
# TYPE lustre_available_kilobytes gauge
lustre_available_kilobytes{component="mgt",target="MGS"} 1874028 1689664819761
lustre_available_kilobytes{component="mdt",target="testfs-MDT0000"} 3388879012 1689664819761

# HELP lustre_free_kilobytes Number of kilobytes allocated to the pool
# TYPE lustre_free_kilobytes gauge
lustre_free_kilobytes{component="mgt",target="MGS"} 1978884 1689664819761
lustre_free_kilobytes{component="mdt",target="testfs-MDT0000"} 3446861004 1689664819761

# HELP lustre_capacity_kilobytes Capacity of the pool in kilobytes
# TYPE lustre_capacity_kilobytes gauge
lustre_capacity_kilobytes{component="mgt",target="MGS"} 1980036 1689664819761
lustre_capacity_kilobytes{component="mdt",target="testfs-MDT0000"} 3446866632 1689664819761