tests: Explicitly drop category from log

Let's disable category here since we don't care about its formatting here.

In any case, every test relying on logging output validation should
always explicitly state the config to avoid issues in the future if
default values change.

Change-Id: Icce09882ef3ed07328679594ff84902383d16c72
Related: OS#5034
diff --git a/tests/lib/ippool_test.c b/tests/lib/ippool_test.c
index 6155ab8..57ab16e 100644
--- a/tests/lib/ippool_test.c
+++ b/tests/lib/ippool_test.c
@@ -132,6 +132,8 @@
 	osmo_init_logging2(tall_ctx, &log_info);
 	log_set_use_color(osmo_stderr_target, 0);
 	log_set_print_filename(osmo_stderr_target, 0);
+	log_set_print_category(osmo_stderr_target, 0);
+	log_set_print_category_hex(osmo_stderr_target, 0);
 
 	srand(time(NULL));