MM-8593 Default APIv3 to disabled for new installs (#8353)

* Default APIv3 to disabled for new installs

* Add EnableAPIv3 setting to client config

* Enable APIv3 for needed tests

utils/config.go

@@ -346,6 +346,7 @@ func GenerateClientConfig(c *model.Config, diagnosticId string, license *model.L
 	props["SiteURL"] = strings.TrimRight(*c.ServiceSettings.SiteURL, "/")
 	props["WebsocketURL"] = strings.TrimRight(*c.ServiceSettings.WebsocketURL, "/")
 	props["SiteName"] = c.TeamSettings.SiteName
+	props["EnableAPIv3"] = strconv.FormatBool(*c.ServiceSettings.EnableAPIv3)
 	props["EnableTeamCreation"] = strconv.FormatBool(c.TeamSettings.EnableTeamCreation)
 	props["EnableUserCreation"] = strconv.FormatBool(c.TeamSettings.EnableUserCreation)
 	props["EnableOpenServer"] = strconv.FormatBool(*c.TeamSettings.EnableOpenServer)