Prevent apt cache from growing over time

**Is your feature request related to a problem? Please describe.**
A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]

**Describe the solution you'd like**
```
for apt_cache_deb in /var/cache/apt/archives/*.deb; do
apt_cache_package=$(dpkg-deb --field "${apt_cache_deb}" Package)
if ! dpkg --list | grep --quiet "^ii ${apt_cache_package} "; then
echo "Deleting unused cache ${apt_cache_deb}"
rm "${apt_cache_deb}"
fi
done
```

**Describe alternatives you've considered**
A clear and concise description of any alternative solutions or features you've considered.

**Additional context**
Add any other context or screenshots about the feature request here.

No file or test is named. Start by locating the repository entry point that installs packages or manages /var/cache/apt/archives, then inspect how that path is exercised. Done means unused .deb files are removed without affecting installed packages and the cache no longer grows indefinitely.

Written by the indexing model from the issue text.