COMP: Ensure designer plugin provided by Qt are also fixed up

In r23042, install rules have been modified to install designer plugin
provided by Qt but the corresponding pattern to select plugins candidate
for fixup has not been adapted. This commit takes care of it.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23559 3bd1e089-480b-0410-8dfb-8563597acbee