[freeflow][rans] update gridvariables in main file necessary for all rans tests

When gridvolumevariables caching is switched on it is necessary to update the gridvariables again in the main file of the tests after the dynamic wall properties are updated in each time.

This can be done with

// update wall properties

problem->updateDynamicWallProperties(sol);

assembler->updateGridVariables(sol);

There might be also be a better solution for this problem but this was the first fix @kweis found. I did not test yet if that changes any reference solutions for the rans problems but it changed a lot in a coupled test we look at.

@nedc This is the fix for the problem we had before christmas in the coupled komega test.