MM-41211: Replaces SessionLength*InDays with SessionLength*InHours. (#19838)

* MM-41211: Replaces SessionLength[Web|Mobile|SSO]InDays with SessionLength[Web|Mobile|SSO]InHours.

* MM-41211: Clear the value of the old config settings.

tests/test-config.json

@@ -36,7 +36,8 @@
         "ExtendSessionLengthWithActivity": true,
         "SessionLengthWebInDays": 30,
         "SessionLengthMobileInDays": 30,
-        "SessionLengthSSOInDays": 30,
+        "SessionLengthSSOInDays": -1,
+        "SessionLengthSSOInHours": 720,
         "SessionCacheInMinutes": 10,
         "SessionIdleTimeoutInMinutes": 0,
         "WebsocketSecurePort": 443,