Remove disabled remains of the performance data (= profiler data + text input) upload feature from the UserReporter from rP8925.

User-submitted text upload was removed in rP12971 in preference of the bugtracker.
Remove leftover mainmenu.js function that this commit should have removed.

Profiler data upload was disabled in rP16213 because the data amount was too large and because the two timing snapshots are inconclusive without further data.
The hereby removed exposed JS functions could have been exploited by JS mods to upload 0ad userdata to arbitrary places.

The performance data upload feature can be redesigned, implemented without JS exposure, with a more transparent privacy policy (refs #5257).

Differential Revision: https://code.wildfiregames.com/D1597
Performance upload feature removal accepted by: Vladislav