apt: Run remove commands noninteractively

I'm seeing ansible hang when trying to remove a package, and the hung
process is `whiptail` like in #2763. It looks like we only use
`APT_ENVVARS` and `DPKG_OPTIONS` for the `apt` commands in install()
and upgrade(). This change uses them in remove() as well, which fixes
the hang.
Merge pull request #3762 from grosskur/fix-apt-noninteractive

apt: Run remove commands noninteractively