balena-rollback/rollback-health: Allow old OS hooks to access efivars

[acostach]

This fixes rollback-health failures for boards like the Jetson Seeeed J4012, which updates efivars for capsule updates from container hooks and not from the current OS hooks. This problem was spotted while running Autokit tests as per internal thread https://balena.zulipchat.com/#narrow/stream/403752-channel.2Fsupport-help/topic/Missing.20binder.20module.20in.20L4T.2FBalenaOS/near/419425908

While the actual HUP works because of /sys being bindmounted by hostapp-update, rollbacks will fail to run the old OS hooks unless efivarfs is mounted.

Change-type: patch

Tested manually on the following configurations:

Seeed J4012

• rollback-altboot from latest cloud image to PR - passed
• rollback-health balena-engine from latest cloud image to PR - passed
• rollback-health vpn from latest cloud image to PR - passed
• rollback-health from PR to PR - passed
• HUP from latest cloud image to PR - passed

Orin NX:

• rollback-health from old cloud image to PR - passed

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• [x] Changes have been tested
  • [x] Covered in automated test suite
  • [x] Manual test case recorded
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