Update soccer_world.cpp

[Ban1p7]

Remove squash and invulnerability stars after goal
Issue #5108

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[Alayan-stk-2]

Thank you for the PR!

However:

• it would be better to do a deeper reset with a call to a dedicated kart function. For example, attachments (bombs, swatters...) also currently persist and should arguably not.
• This won't be merged before 1.5 is out.