pid1: fix coredump_filter setting

Correct what appears to be a copy/paste error in config_parse_exec_coredump_filter that is preventing the coredump_filter setting from working correctly.

src/core/load-fragment.c

@@ -800,7 +800,7 @@ int config_parse_exec_coredump_filter(
         }
 
         c->coredump_filter |= f;
-        c->oom_score_adjust_set = true;
+        c->coredump_filter_set = true;
         return 0;
 }