Make ca command silently use default if .attr file does not exist

Reviewed-by: NNicola Tuveri <nic.tuv@gmail.com>
Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7286)

(cherry picked from commit ac454d8d4663e2fcf8a8437fab8aefd883091c37)

apps/apps.c

@@ -1561,7 +1561,7 @@ CA_DB *load_index(const char *dbfile, DB_ATTR *db_attr)
 #else
     BIO_snprintf(buf, sizeof(buf), "%s-attr", dbfile);
 #endif
-    dbattr_conf = app_load_config(buf);
+    dbattr_conf = app_load_config_quiet(buf);
 
     retdb = app_malloc(sizeof(*retdb), "new DB");
     retdb->db = tmpdb;