update-oojs-ui.sh: Exclude the minimised distribution files

Introduced by Ic8f8194. Also removing unneeded exclusion of non-existant
unthemed CSS file after Ieb27c3fd.

Change-Id: Ib0293695764ac32b8aac3be7c4f37b72cbd72561
Merge "update-oojs-ui.sh: Exclude the minimised distribution files"