Prevent error when workers config not found, throw warning instead

Related: https://progress.opensuse.org/issues/181409

Author: Wabri

lib/OpenQA/Worker/Settings.pm

@@ -23,7 +23,8 @@ use constant VNCPORT_OFFSET => $ENV{VNCPORT_OFFSET} // 90;
 sub new ($class, $instance_number = undef, $cli_options = {}) {
     my $config_paths = lookup_config_files(undef, 'workers.ini', 1);
     my $cfg = parse_config_files($config_paths);
-    my @parse_errors = @$config_paths ? (@Config::IniFiles::errors) : ('No config file found.');
+    my @parse_errors = @$config_paths ? (@Config::IniFiles::errors) : ();
+    log_warning "[OpenQA::Worker::Settings] workers.ini not found, using default settings\n" unless @$config_paths;
 
     # read settings from config
     my %global_settings;