[CLD-7029] Add a new system console page for configuring custom export FileSettings (#26034)

* Add a new system console page for configuring custom export FileSettings

* Remove NONE option for ExportDriverName dropdown

* Fix tests

* Fix i18n

* Update webapp/channels/src/components/admin_console/admin_definition.tsx

Co-authored-by: Ben Schumacher <ben.schumacher@mattermost.com>

* PR Feedback

* Fix formatting

* gofmt

---------

Co-authored-by: Mattermost Build <build@mattermost.com>
Co-authored-by: Ben Schumacher <ben.schumacher@mattermost.com>

server/channels/api4/system.go

@@ -535,11 +535,6 @@ func testS3(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	if *c.App.Config().ExperimentalSettings.RestrictSystemAdmin {
-		c.Err = model.NewAppError("testS3", "api.restricted_system_admin", nil, "", http.StatusForbidden)
-		return
-	}
-
 	appErr := c.App.CheckMandatoryS3Fields(&cfg.FileSettings)
 	if appErr != nil {
 		c.Err = appErr

server/channels/api4/system_test.go

@@ -589,15 +589,6 @@ func TestS3TestConnection(t *testing.T) {
 		CheckErrorID(t, err, "api.file.test_connection_s3_auth.app_error")
 	})
 
-	t.Run("as restricted system admin", func(t *testing.T) {
-		th.App.UpdateConfig(func(cfg *model.Config) { *cfg.ExperimentalSettings.RestrictSystemAdmin = true })
-		defer th.App.UpdateConfig(func(cfg *model.Config) { *cfg.ExperimentalSettings.RestrictSystemAdmin = false })
-
-		resp, err := th.SystemAdminClient.TestS3Connection(context.Background(), &config)
-		require.Error(t, err)
-		CheckForbiddenStatus(t, resp)
-	})
-
 	t.Run("empty file settings", func(t *testing.T) {
 		config.FileSettings = model.FileSettings{}
 		resp, err := th.SystemAdminClient.TestS3Connection(context.Background(), &config)