Fix staff debug module field table width.
Fix staff debug module field table width.

The auto-adjusting table layout would get illegible for certain types
of problems that contain a large amount of data because the first column
could get very narrow (down to the width of a single character).

This commit fixes the width of the first column to 25%.

caesar2164/edx-platform,Stanford-Online/edx-platform,Stanford-Online/edx-platform,Stanford-Online/edx-platform,caesar2164/edx-platform,caesar2164/edx-platform,caesar2164/edx-platform,Stanford-Online/edx-platform