Disable Russian translation since it's incomplete

The maintainer of this translation didn't want to continue spending time to keep his translation up-to-date.

Contributes to issue CURA-4601.

resources/qml/Preferences/GeneralPage.qml

@@ -159,7 +159,7 @@ UM.PreferencesPage
                             append({ text: "Nederlands", code: "nl_NL" })
                             append({ text: "Polski", code: "pl_PL" })
                             append({ text: "Português do Brasil", code: "pt_BR" })
-                            append({ text: "Русский", code: "ru_RU" })
+                            //Russian is disabled for being incomplete: append({ text: "Русский", code: "ru_RU" })
                             append({ text: "Türkçe", code: "tr_TR" })
                             append({ text: "简体中文", code: "zh_CN" })