Revert "units: set NoNewPrivileges= for all long-running services"

Revert "units: set NoNewPrivileges= for all long-running services"

This reverts commit 3ca9940cb95cb263c6bfe5cfee72df232fe46a94.

Let's split the commit in two: the sorting and the changes.
Because there's a requirement to update selinux policy, this change is
incompatible, strictly speaking. I expect that distributions might want to
revert this particular change. Let's make it easy.