Summary: Strip environment variables in lxqt-sudo
Test Plan:
1. Test first with lxqt-sudo from repo: lxqt-sudo env 2> env.txt
2. Install this version
3. Run lxqt-sudo env 2> env2.txt
4. Compare env.txt with env2.txt: diff -y env.txt env2.txt
5. Both files should differ in most environment variables, such as HOME
Reviewers: tsimonq2, wxl
Reviewed By: tsimonq2
Differential Revision: https://phab.lubuntu.me/D44