Remove described qualitative size of sphere in mass spheres' dynamic descriptions

[terracoda]

@zepumph, in issue phetsims/gravity-force-lab#128 qualitative size was correctly removed from the aria-valuetext, however, I would also like it removed from dynamic descriptions in the PDOM for both simulations, BASICS and REGULAR.

I am adding screen shots for both sims, red lines strike out the size information that I would like removed.

GFL BASICS

GFL REGULAR

Note to self (@terracoda) this change has already been noted in design document.

[terracoda]

@zepumph, because this change is the same for both sims, I think it might be an easy one to implement.

[zepumph]

Assigning to @terracoda to work on further. At our meeting we were not totally sure if we want to remove them in both, or just BASICS.

[terracoda]

@zepumph, yes, the actual described size of the spheres is not needed, and it has already been removed.

Only the comparative size is needed and that will be looked after in issue #96.

Closing this issue.