[LU-8691] ha.sh improvements: add mdtest, add simultaneous victim nodes failover

• Type: Improvement
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.11.0
• Affects Version/s: Lustre 2.8.0
• Labels: patch
• Assignee: Jian Yu
• Reporter: Elena Gryaznova

Description

Seagate customers use mdtest load on failover/failback tests and perform failover of several osts simultaneously.
Proposed patch adds:

• mdtest mpi load;
• ha_simultaneous mode, which allows to reboot
  victim nodes simultaneously.