[REG 5.15 -> 6.0] TR_EXCLUDE became too strict

In commit https://codereview.qt-project.org/c/qt/qttools/+/295830, lupdate was ported from QRegExp to QRegularExpression.

Before that change, a pattern like

TR_EXCLUDE += /home/egon/dev/vcpkg/installed/x64-linux/include/*

Would exclude files in the directory /home/egon/dev/vcpkg/installed/x64-linux/include and all subdirectories.

The internal regular expression object looked like this:
 

QRegExp(patternSyntax=1, pattern='"/home/egon/dev/vcpkg/installed/x64-linux/include/*"')

After the said change, the produced regular expression would match only the directory because the regular expression is anchored:

QRegularExpression("\\A(?:/home/egon/dev/vcpkg/installed/x64-linux/include/[^/]*)\\z", QRegularExpression::PatternOptions("NoPatternOption"))

This makes the usage of QMake's TR_EXCLUDE and CMake's QT_EXCLUDE_SOURCES_FROM_TRANSLATION needlessly laborsome. See this comment in QTBUG-27936 for an example