[PDI-10277]: Fixed setting of parameters in Pan

- Param values were not being overridden in the TransMeta object, so during runtime if a step looks for the parameter value from the TransMeta, it will get the default value as set in the transformation metadata (ktr file, e.g.)

- Moved parameter-related code to its own method to facilitate unit testing

- Added unit test for the new method and specifically as a regression test for PDI-10277

- Applied formatting rules to ensure no CheckStyle violations