journald-server: drop spuriously doubled '=' for OBJECT_SYSTEMD_INVOC…

…ATION_ID

(cherry picked from commit 6cb8286)

src/journal/journald-server.c

@@ -1111,7 +1111,7 @@ static void server_dispatch_message_real(
                 IOVEC_ADD_STRING_FIELD(iovec, n, o->slice, "OBJECT_SYSTEMD_SLICE");
                 IOVEC_ADD_STRING_FIELD(iovec, n, o->user_slice, "OBJECT_SYSTEMD_USER_SLICE");
 
-                IOVEC_ADD_ID128_FIELD(iovec, n, o->invocation_id, "OBJECT_SYSTEMD_INVOCATION_ID=");
+                IOVEC_ADD_ID128_FIELD(iovec, n, o->invocation_id, "OBJECT_SYSTEMD_INVOCATION_ID");
         }
 
         assert(n <= m);