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: Ia633cae0a26f294e276b431a82256abb1b57ebba
Related: OS#5034
diff --git a/src/tests/test_common.c b/src/tests/test_common.c
index 7c6f62a..0729368 100644
--- a/src/tests/test_common.c
+++ b/src/tests/test_common.c
@@ -86,6 +86,8 @@
 
 	log_set_print_filename(osmo_stderr_target, 0);
 	log_set_use_color(osmo_stderr_target, 0);
+	log_set_print_category(osmo_stderr_target, 0);
+	log_set_print_category_hex(osmo_stderr_target, 0);
 	return rc;
 }