Issue 49035 - dbmon.sh shows pages-in-use that exceeds the cache size
Bug Description: dbmon shows negative free cache stats because the pages-in-use exceeds
the expected size of the cache. This is because on caches smaller
than 500mb, libdb automatically increases the size by ~25%. The tool
is only checking the configured db cache size, and in this case its
actaully larger than what was conigured in dse.ldif.
Fix Description: dbmon.sh should use the libdb's "cache size in bytes", instead of
nsslapd-dbcachesize - as it could be different.
https://pagure.io/389-ds-base/issue/49035
Reviewed by: nhosoi & wibrown (Thanks!!)
(cherry picked from commit 84ec26129744492a387e39ae5bf236f49863ee59)