Revert "sysusers: properly mark generated accounts as locked"

This reverts the gist of commit 636e72bce6.
The comment and the tiny cleanup are left alone.

We shouldn't lock the accounts because people actually need to use them, and
if they are locked, various tools will refuse.
See https://github.com/systemd/systemd/pull/13277#issuecomment-529964578
and follow-up comments.

src/sysusers/sysusers.c

@@ -528,7 +528,7 @@ static int write_temporary_shadow(const char *shadow_path, FILE **tmpfile, char
                         .sp_max = -1,
                         .sp_warn = -1,
                         .sp_inact = -1,
-                        .sp_expire = i->uid == 0 ? -1 : 1, /* lock account as a whole, unless this is root */
+                        .sp_expire = -1,
                         .sp_flag = (unsigned long) -1, /* this appears to be what everybody does ... */
                 };