feat(xva): improve compatibility with xenserver

[fbeauchamp]

• from ticket 23636
• fix error (Failure "Field last_boot_CPU_flags not present in rpc")
• fix error (Failure "(Failure "Field suspend_VDI not present in rpc"")
• fix error (Failure "(Failure "Field suspend_SR not present in rpc"")

Description

Short explanation of this PR (feel free to re-use commit message)

Checklist

• Commit
  • Title follows commit conventions
  • Reference the relevant issue (Fixes #007, See xoa-support#42, See https://...)
  • If bug fix, add Introduced by
• Changelog
  • If visible by XOA users, add changelog entry
  • Update "Packages to release" in CHANGELOG.unreleased.md
• PR
  • If UI changes, add screenshots
  • If not finished or not tested, open as Draft