Use {{int:templatesandbox-suffix}} in {{int:templatesandbox-text}}

As I observed, some translators translated the path with the suffix
(sandbox), which isn't the same as its translation in
{{int:templatesandbox-text}}. This may confuse the user. To avoid this,
the actual translation from the appropriate message is used.

Change-Id: I85a1d38256905c9e1d6f2bde07c112adcd0f12fb
Merge "Use {{int:templatesandbox-suffix}} in {{int:templatesandbox-text}}"