Take into account that mysql services start even with
invalid defaults files (using data file relative to mysqld.exe location).
Handle this case in upgrade scenarios, as if there was no
--defaults-file in service definition.
mysqld --install without any parameters.
In such case, service name is always MYSQL, as service
binary path is "path\to\mysqld.exe" "MySQL". Guess data
directory it is either from my.ini (which is assumed to
be in the installation root), or just data directory
under install root.
