Mirror should PANIC immediately when recovery is in consistent state but
there are existing invalid page entries in invalid_page hash table. This
makes sure to not delay the checking till mirror is promoted and helps
catching the file missing problems on mirror sooner. The logic of mirror
immediate PANIC was introduced in upstream commit 1e616f63. Since, no
test exist for this in upstream and logic is used by AO tables as well,
this patch is adding test to validate the stated behavior.
Co-authored-by: NAshwin Agrawal <aagrawal@pivotal.io>