PLT-5900 Removed automatic configuration of SiteURL (#5952)

* Revert "PLT-5765 Passed SiteURL to SendNotifications (#5705)"

This reverts commit a8e68bd890.

* Removed automatic configuration of SiteURL

* Reverted unintentional config changes

* Updated help text

* Added link to docs in Site URL warning

* Fixed merge conflict

einterfaces/saml.go

@@ -10,7 +10,7 @@ import (
 type SamlInterface interface {
 	ConfigureSP() *model.AppError
 	BuildRequest(relayState string) (*model.SamlAuthRequest, *model.AppError)
-	DoLogin(encodedXML string, relayState map[string]string, siteURL string) (*model.User, *model.AppError)
+	DoLogin(encodedXML string, relayState map[string]string) (*model.User, *model.AppError)
 	GetMetadata() (string, *model.AppError)
 }