core: improve the logic that implies no new privileges

The no_new_privileged_set variable is not used any more since commit
9b232d3241 that fixed another thing. So remove it. Also no
need to check if we are under user manager, remove that part too.

src/core/execute.c

@@ -2201,7 +2201,8 @@ static bool context_has_no_new_privileges(const ExecContext *c) {
         if (have_effective_cap(CAP_SYS_ADMIN)) /* if we are privileged, we don't need NNP */
                 return false;
 
-        return context_has_address_families(c) || /* we need NNP if we have any form of seccomp and are unprivileged */
+        /* We need NNP if we have any form of seccomp and are unprivileged */
+        return context_has_address_families(c) ||
                 c->memory_deny_write_execute ||
                 c->restrict_realtime ||
                 exec_context_restrict_namespaces_set(c) ||