Add RHEL 7 for SAP ELS to the RHUI config (oamg#1254)

There is going to be a separate ELS RHUI client package for
RHEL 7 for SAP.

(cherry picked from commit 4ba0ec3)

repos/system_upgrade/common/libraries/rhui.py

@@ -319,6 +319,7 @@ def mk_rhui_setup(clients=None, leapp_pkg='', mandatory_files=None, optional_fil
     ],
     RHUIFamily(RHUIProvider.GOOGLE, variant=RHUIVariant.SAP, client_files_folder='google-sap'): [
         mk_rhui_setup(clients={'google-rhui-client-rhel79-sap'}, os_version='7', content_channel=ContentChannel.E4S),
+        mk_rhui_setup(clients={'google-rhui-client-rhel7-sap-els'}, os_version='7'),
         mk_rhui_setup(clients={'google-rhui-client-rhel8-sap'}, leapp_pkg='leapp-rhui-google-sap',
                       mandatory_files=[('leapp-google-sap.repo', YUM_REPOS_PATH)],
                       files_supporting_client_operation=['leapp-google-sap.repo'],