config: remove explicit setting of required property to true for options with a default value

See #5551

backend/koofr/koofr.go

@@ -34,18 +34,15 @@ func init() {
 			Name:     "endpoint",
 			Help:     "The Koofr API endpoint to use.",
 			Default:  "https://app.koofr.net",
-			Required: true,
 			Advanced: true,
 		}, {
 			Name:     "mountid",
 			Help:     "Mount ID of the mount to use.\n\nIf omitted, the primary mount is used.",
-			Default:  "",
 			Advanced: true,
 		}, {
 			Name:     "setmtime",
 			Help:     "Does the backend support setting modification time.\n\nSet this to false if you use a mount ID that points to a Dropbox or Amazon Drive backend.",
 			Default:  true,
-			Required: true,
 			Advanced: true,
 		}, {
 			Name:     "user",

backend/tardigrade/fs.go

@@ -86,7 +86,6 @@ func init() {
 			{
 				Name:    fs.ConfigProvider,
 				Help:    "Choose an authentication method.",
-				Required: true,
 				Default: existingProvider,
 				Examples: []fs.OptionExample{{
 					Value: "existing",

backend/union/union.go

@@ -35,22 +35,18 @@ func init() {
 		}, {
 			Name:    "action_policy",
 			Help:    "Policy to choose upstream on ACTION category.",
-			Required: true,
 			Default: "epall",
 		}, {
 			Name:    "create_policy",
 			Help:    "Policy to choose upstream on CREATE category.",
-			Required: true,
 			Default: "epmfs",
 		}, {
 			Name:    "search_policy",
 			Help:    "Policy to choose upstream on SEARCH category.",
-			Required: true,
 			Default: "ff",
 		}, {
 			Name:    "cache_time",
 			Help:    "Cache time of usage and free space (in seconds).\n\nThis option is only useful when a path preserving policy is used.",
-			Required: true,
 			Default: 120,
 		}},
 	}