arc: add a few invariant checks in release builds of 2.4

[andriytk]

Convert a couple ASSERTs invariants to VERIFYs to enforce them in release builds to be able to root-case #18782 kernel panic, whenever it happens again.

Reviewed-by: Brian Behlendorf behlendorf1@llnl.gov

Closes #18840
(cherry picked from commit 023d44b)

Motivation and Context

Description

How Has This Been Tested?

Types of Changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Quality assurance (non-breaking change which makes the code more robust against bugs)
• Breaking change (fix or feature that would cause existing functionality to change)
• Library ABI change (libzfs, libzfs_core, libnvpair and libzfsbootenv)
• Documentation (a change to man pages or other documentation)

Checklist

• My code follows the OpenZFS code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied.
• All commit messages are properly formatted and contain Signed-off-by.