In general, it's not very usuful to repeat the unit name as the description.
Especially when the word is a common name and if somebody doesn't understand
the meaning immediately, they are not going to gain anything from the
repeat either, e.g. "halt", "swap".
In the status-unit-format=combined output parentheses are used around
Description, so avoid using parenthesis in the Description itself.
This makes things a bit simpler and the build a bit faster, because we don't
have to rewrite files to do the trivial substitution. @rootbindir@ is always in
our internal $PATH that we use for non-absolute paths, so there should be no
functional change.
