test-sd-device: drop chunk added by mistake

I initially wrote it this way, but then decided to implement a loop
limit, but forgot to drop the first approach in one place.
Fixup for 74cb65e45f.

src/libsystemd/sd-device/test-sd-device.c

@@ -488,8 +488,6 @@ TEST(sd_device_enumerator_add_match_parent) {
         ASSERT_OK(sd_device_enumerator_allow_uninitialized(e));
         exclude_problematic_devices(e);
 
-        ASSERT_OK(sd_device_enumerator_add_match_subsystem(e, "memory", false));
-
         if (!slow_tests_enabled())
                 ASSERT_OK(sd_device_enumerator_add_match_subsystem(e, "block", true));