Replace first disk on storage1.staging

In order to test the seagate replacement procedure, only one disk will be replaced through the manufacturer warranty :

/dev/sda / SLOT 00 Model Family: Seagate Enterprise Capacity 3.5 HDD Device Model: ST6000NM0115-1YZ110 Serial Number: ZAD0S2NR

The disk was excluded from the zfs pool so it can be replaced without side effects

---

Migrated from T3033 (view on Phabricator)