FfU doesn't delete its caches after self-update

[TPS]

Describe the bug FfU should delete internal caches when self-updating, so App Info caches shouldn't be multi-MB.

To Reproduce Please insert the steps to reproduce the behavior here:

1. Wait for (GitHub-based) FfU to have an update.
2. Self-update.
3. Open, refresh, & then "close" FfU (however).
4. Check cache sizes in App Info.

Expected behavior Caches should be effectively 0 (say, < 1 MB).

Error message from FFUpdater No crash, so no trace.