Clear unafforable cost slots in rjSS update, not only when entering the screen

[Xymanek]

Fixes #698

Currently pending the launch button update resolution

https://github.com/robojumper/robojumperSquadSelect/blob/d78cd1bf18fa864e5b3d5f9511f767b0876aeb86/robojumperSquadSelect/Src/robojumperSquadSelect/Classes/robojumper_UISquadSelect.uc#L1594-L1598

[Xymanek]

Notes for patch notes:

• Previous logic (only on UICAG -> UISS transition) was broken anyway as it was missing ModifyStateObject, so depending on circumstances it could've simply been "unapplied"
• Current logic properly handles all cases, but...
• Due to the rjSS issue mentioned above, the launch button will stay disabled until you go somewhere else (build items (again), soldier menus, back to UICAG, etc). RoboJumper promised an update at some point
  • It's not a huge deal anyway, since usually after you build an item you would want to equip it, applying the above fix