Change search string of CMake build directories for Qt Creator 6

Qt Creator can import existing CMake build directories. Qt Creator 5 scans all directories starting with "build", but in Qt Creator 6 refactoring was done and the search string was changed to "build." (superfluous dot at the end).

This is because the developer probably thought that the search string must be a regular expression, but it is just a wildcard filter as documented here https://doc.qt.io/qt-6/qdir.html#setNameFilters. The patch restores the old behavior from Qt Creator 5.