this is executed when ha_columnstore is loaded, at dlopen time
before any initialization code is run and crashes any dlopen
attemps.
Crashes - because a missing config file is a crashing offence,
but it's an issue for another day
This patch fixes:
MCOL-3557 - Row Based Replication events to ColumnStore tables will no
longer cause MariaDB to crash, it will error instead.
MCOL-3556 - Remove the Columnstore.xml variable to turn on ColumnStore
tables applying replication events and instead make it a system variable
that can be set in my.cnf called "columnstore_replication_slave". This
allows it to be set per-UM.
