Fixes related to "Installing Prerequisites" status

[arielj]

This fixes 2 issues:

• we were showing the Installing Prerequisites for GOG games but we don't really do that yet
• we were setting the Installing Prerequisites status when running an exe on the prefix but never resetting that state

I also moved the Installing Prerequisites status for the Amazon setup to be displayed after the prefix is verified instead of before, to happen right before the post install step.

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Use the following Checklist if you have changed something on the Backend or Frontend:

• Tested the feature and it's working on a current and clean install.
• Tested the main App features and they are still working on a current and clean install. (Login, Install, Play, Uninstall, Move games, etc.)
• Created / Updated Tests (If necessary)
• Created / Updated documentation (If necessary)

[Etaash-mathamsetty]

Looks good