Utils: Remove FilePath::operator+()

This was a alias for .stringAppended(), but can be used too easily
when .pathAppended() is meant.

Change-Id: Ia3b64d39828d4074b43d87c923ce3a6a87038948
Reviewed-by: Christian Stenger <christian.stenger@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>

src/libs/utils/filepath.cpp

@@ -586,7 +586,7 @@ static FilePaths appendExeExtensions(const Environment &env, const FilePath &exe
             const QStringList extensions = env.expandedValueForKey("PATHEXT").split(';');
 
             for (const QString &ext : extensions)
-                execs << executable + ext.toLower();
+                execs << executable.stringAppended(ext.toLower());
         }
     }
     return execs;
@@ -971,11 +971,6 @@ bool FilePath::operator>=(const FilePath &other) const
     return !(*this < other);
 }
 
-FilePath FilePath::operator+(const QString &s) const
-{
-    return stringAppended(s);
-}
-
 /// \returns whether FilePath is a child of \a s
 bool FilePath::isChildOf(const FilePath &s) const
 {