Do not check unlogged indexes on standby

Hi hackers!

Currently, if we check indexes on standby we often get

man-psbpshn0skhsxynd/xiva_xtable_testing_01 R # select bt_index_check('xiva_loadtest.pk_uid');
ERROR:  58P01: could not open file "base/16453/125407": No such file or directory

I think that we should print warning and that's it. Amcheck should not give false positives.

Or, maybe, there are some design considerations that I miss?


BTW I really want to enable rightlink-leftlink invariant validation on standby..

Thanks!

Best regards, Andrey Borodin.