flent: Use qt5.15 just like pyqt5 use in it (#99956)

Bonus: Spare double wrapping.

pkgs/applications/networking/flent/default.nix

@@ -25,10 +25,8 @@ buildPythonApplication rec {
     xvfb-run -s '-screen 0 800x600x24' ./test-runner
   '';
 
-  postInstall = ''
-    for program in $out/bin/*; do
-      wrapQtApp $program --prefix PYTHONPATH : $PYTHONPATH
-    done
+  preFixup = ''
+    makeWrapperArgs+=("''${qtWrapperArgs[@]}")
   '';
 
   meta = with stdenv.lib; {

pkgs/top-level/all-packages.nix

@@ -3703,7 +3703,7 @@ in
 
   flashrom = callPackage ../tools/misc/flashrom { };
 
-  flent = python3Packages.callPackage ../applications/networking/flent { qt5 = qt514; };
+  flent = python3Packages.callPackage ../applications/networking/flent { };
 
   flpsed = callPackage ../applications/editors/flpsed { };