test oracle 23c, mariadb12; reduce backend use

test oracle 23c, mariadb12; reduce backend use

one particular vector test wont run on oracle 23c free, so
just disable it.

added better skips for the rest of the vector tests and
fixed a deprecation issue.

this will be the first run on the new oracle23 on CI so we'll have to
see how this goes.

Also adjust for mariabdb12 being overly helpful with regards
to stale row updates.

as we are having trouble getting 23c to pass throug transaction
tests, i noted we have an explosion of tests due to the multiple
drivers, so this patch introduces __sparse_driver_backend__
for all tests where we want variety of
database server but there's no need to test every driver.
This should dramatically reduce the size of the test suite run

Change-Id: Ic8d3eb0a60e76b4c54c6bb4a721f90c81ede782b