Few fixes in mysql utility module and testsuite

I am not sure I want to take this direction.
Current state matches what I wanted to do - to have per test memory context.
In my mind, talloc_autofree_context() is to be used in cases when you want to
have a memory for the lifetime of the problem - something like "dynamic globals".

In short, I would prefer to keep it that way and this pretty much serves my next
patches that check/fix memory leaks :)