Fix incorrect use of ts when setting custom data form title

[colemanw]

Overview

Fix incorrect string translation. English variable names should not be inserted into the translated string as they will be untranslatable.

Before

Untranslatable strings "Add" "Edit" "Copy"

After

Fixed.

Comments

Also removed redundant CRM_Utils_Request::retrieve('mode' because the same call is made 5 lines above.

[civibot]

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[demeritcowboy]

This works and translates properly and looks good.

Aside: There's also a "View %1 Record" which is elsewhere but which is already ok, just now is slightly inconsistent since it still has the word "record".

[eileenmcnaughton]

Merging based on @demeritcowboy's review